How to fix GCM limit of 1000, need to send message to 15000 devices,

i have a script which is used to send GCM to android, but unfortunately it stops working after 1000 messages, can anyone fix this code so that it can work after 1000 users also, the error i receive is "Number of messages on bulk (1412) exceeds maximum allowed (1000)" here is the php code below:

<?php

$gcm_result = "should be empty";

$version = get_bloginfo('version');
if ($version < 3.8) {
function px_gcm_menu() {
    add_menu_page('GCM', 'GCM', 'manage_options', 'px-gcm','');
    add_submenu_page( 'px-gcm', __('New Message','px_gcm'), __('New Message','px_gcm'), 'manage_options', 'px-gcm', 'px_display_page_msg');
    add_submenu_page( 'px-gcm', __('All Devices','px_gxm'), __('All Devices','px_gxm'), 'manage_options', 'px-gcm-devices', 'px_display_devices');
    add_submenu_page( 'px-gcm', __('Stats','px_gxm'), __('Stats','px_gxm'), 'manage_options', 'px-gcm-stats', 'px_display_stats');
    add_submenu_page( 'px-gcm', __('Export','px_gxm'), __('Export','px_gxm'), 'manage_options', 'px-gcm-export', 'px_display_export');
    add_submenu_page( 'px-gcm', __('Settings','px_gcm'), __('Settings','px_gcm'), 'manage_options', 'px-gcm-settings', 'px_display_page_setting');
}
add_action('admin_menu', 'px_gcm_menu');
}else { 
function px_gcm_menu() {
    add_menu_page('GCM', 'GCM', 'manage_options', 'px-gcm','','dashicons-cloud');
    add_submenu_page( 'px-gcm', __('New Message','px_gcm'), __('New Message','px_gcm'), 'manage_options', 'px-gcm', 'px_display_page_msg');
    add_submenu_page( 'px-gcm', __('All Devices','px_gxm'), __('All Devices','px_gxm'), 'manage_options', 'px-gcm-devices', 'px_display_devices');
    add_submenu_page( 'px-gcm', __('Stats','px_gxm'), __('Stats','px_gxm'), 'manage_options', 'px-gcm-stats', 'px_display_stats');
    add_submenu_page( 'px-gcm', __('Export','px_gxm'), __('Export','px_gxm'), 'manage_options', 'px-gcm-export', 'px_display_export');
    add_submenu_page( 'px-gcm', __('Settings','px_gcm'), __('Settings','px_gcm'), 'manage_options', 'px-gcm-settings', 'px_display_page_setting');  
}
add_action('admin_menu', 'px_gcm_menu');
}

/*
*
* All the functions for the settings page
*
*/
function px_register_settings() {
add_settings_section('gcm_setting-section', '', 'gcm_section_callback', 'px-gcm');
add_settings_field('api-key', __('Api Key','px_gcm'), 'api_key_callback', 'px-gcm', 'gcm_setting-section');
add_settings_field('snpi', __('New post info','px_gcm'), 'snpi_callback', 'px-gcm', 'gcm_setting-section');
add_settings_field('supi', __('Updated post info','px_gcm'), 'supi_callback', 'px-gcm', 'gcm_setting-section');
add_settings_field('abd', __('Display admin bar link','px_gcm'), 'abd_callback', 'px-gcm', 'gcm_setting-section' );
add_settings_field('debug', __('Show debug response','px_gcm'), 'debug_callback', 'px-gcm', 'gcm_setting-section' );
register_setting( 'px-gcm-settings-group', 'gcm_setting', 'px_gcm_settings_validate' );
}

 // load the translations
 function px_gcm_load_textdomain() {
  load_plugin_textdomain( 'px_gcm', false, basename( dirname( __FILE__ ) ) . '/lang' ); 
}

function gcm_section_callback() {
echo __('Required settings for the plugin and the App.','px_gcm');
}

function api_key_callback() {
$options = get_option('gcm_setting');
?>
<input type="text" name="gcm_setting[api-key]" size="41" value="<?php echo $options['api-key']; ?>" />
<?php
}

function snpi_callback(){
$options = get_option('gcm_setting');
$html = '<input type="checkbox" id="snpi" name="gcm_setting[snpi]" value="1"' . checked(1, $options['snpi'], false) . '/>';
echo $html;
}

function supi_callback(){
$options = get_option('gcm_setting');
$html= '<input type="checkbox" id="supi" name="gcm_setting[supi]" value="1"' . checked(1, $options['supi'], false) . '/>';
echo $html;
}

function abd_callback() {
$options = get_option('gcm_setting');
$html = '<input type="checkbox" id="abd" name="gcm_setting[abd]" value="1"' . checked(1, $options['abd'], false) . '/>';
echo $html;
}

function debug_callback() {
$options = get_option('gcm_setting');
$html = '<input type="checkbox" id="debug" name="gcm_setting[debug]" value="1"' . checked(1, $options['debug'], false) . '/>';
echo $html;
}

function px_gcm_settings_validate($arr_input) {
$options = get_option('gcm_setting');

if(isset($arr_input['api-key'])) {
    $options['api-key'] = trim($arr_input['api-key']);
}
if(isset($arr_input['snpi'])) {
    $options['snpi'] = trim($arr_input['snpi']);
}
if(isset($arr_input['supi'])) {
    $options['supi'] = trim($arr_input['supi']);
}
if(isset($arr_input['abd'])) {
    $options['abd'] = trim($arr_input['abd']);
}
if(isset($arr_input['debug'])) {
    $options['debug'] = trim($arr_input['debug']);
}

return $options;
}

/*
*
* Send notification for post update
*
*/
function px_update_notification($new_status, $old_status, $post) {
$options = get_option('gcm_setting');
if($options['snpi'] != false){
    if ($old_status == 'publish' && $new_status == 'publish' && 'post' == get_post_type($post)) {
        $post_title = get_the_title($post);
        $post_url = get_permalink($post);      
        $post_id = get_the_ID($post);
        $post_author = get_the_author_meta('display_name', $post->post_author);
        $message = $post_title . ";" . $post_url . ";". $post_id . ";" . $post_author . ";";

        // Send notification
        $up = "update";
        px_sendGCM($message, $up, 010);
    }
    }
    }

/*
*
* Send notification for new post
*
*/
function px_new_notification($new_status, $old_status, $post) {
$options = get_option('gcm_setting');
if($options['snpi'] != false){
    if ($old_status != 'publish' && $new_status == 'publish' && 'post' == get_post_type($post)) {
        $post_title = get_the_title($post);
        $post_url = get_permalink($post);
        $post_id = get_the_ID($post);
        $post_author = get_the_author_meta('display_name', $post->post_author);
        $message = $post_title . ";" . $post_url . ";". $post_id . ";" . $post_author . ";";

        // Send notification
        $np = "new_post";
        px_sendGCM($message, $np, 010);
    }
}
}

/*
*
* Register ToolBar
*
*/
function px_gcm_toolbar() {
$options = get_option('gcm_setting');
if($options['abd'] != false){
    global $wp_admin_bar;
    $page = get_site_url().'/wp-admin/admin.php?page=px-gcm';
    $args = array(
        'id'     => 'px_gcm',
        'title'  => '<img class="dashicons dashicons-cloud">GCM</img>', 'px_gcm',
        'href'   =>  "$page" );

    $wp_admin_bar->add_menu($args);
}
}

/*
*
* GCM Send Notification
*
*/
function px_sendGCM($message, $type, $regid) {
global $wpdb;
$px_table_name = $wpdb->prefix.'gcm_users';
$options = get_option('gcm_setting');
$apiKey = $options['api-key'];
$url = 'http://ift.tt/YbbTRA';
$result;
$id;

if($regid == 010) {
    $id = px_getIds();
}else {
    $id = $regid;
}

if($id == 010 && $id >= 1000){
    $newId = array_chunk($id, 1000);
    foreach ($newId as $inner_id) {
        $fields = array(
            'registration_ids' => $inner_id,
            'data' => array($type => $message) 
        );

        $headers = array(
            'Authorization' => 'key=' . $apiKey,
            'Content-Type' => 'application/json'
        );

        $result = wp_remote_post($url, array(
            'method' => 'POST',
            'headers' => $headers,
            'httpversion' => '1.0',
            'sslverify' => false,
            'body' => json_encode($fields) )
        );
    }
}else {
    $fields = array(
        'registration_ids' => $id,
        'data' => array($type => $message)
    );

    $headers = array(
        'Authorization' => 'key=' . $apiKey,
        'Content-Type' => 'application/json'
    );

    $result = wp_remote_post($url, array(
        'method' => 'POST',
        'headers' => $headers,
        'httpversion' => '1.0',
        'sslverify' => false,
        'body' => json_encode($fields))
    );

}

$msg = $result['body'];
$answer = json_decode($msg);
$cano = px_canonical($answer);
$suc = $answer->{'success'};
$fail = $answer->{'failure'};
$options = get_option('gcm_setting');
if($options['debug'] != false){
    $inf= "<div id='message' class='updated'><p><b>".__('Message sent.','px_gcm')."</b><i>&nbsp;&nbsp;($message)</i></p><p>$msg</p></div>";
}else {
    $inf= "<div id='message' class='updated'><p><b>".__('Message sent.','px_gcm')."</b><i>&nbsp;&nbsp;($message)</i></p><p>".__('success:','px_gcm')." $suc  &nbsp;&nbsp;".__('fail:','px_gcm')." $fail </p></div>";
}

// Updating stats
$suc_num = get_option('px_gcm_suc_msg', 0);
update_option('px_gcm_suc_msg', $suc_num+$suc);
$fail_num = get_option('px_gcm_fail_msg', 0);
update_option('px_gcm_fail_msg', $fail_num+$fail);
$total_msg = get_option('px_gcm_total_msg', 0);
update_option('px_gcm_total_msg', $total_msg+1);
for($i=0; $i < count($id); $i++) {
    $temp = $id[$i];
    $send_msg = $wpdb->get_row("SELECT send_msg FROM $px_table_name WHERE gcm_regid='$temp' ");
    $new_num = $send_msg->send_msg+1;
    $upquery = "UPDATE $px_table_name SET send_msg=$new_num WHERE gcm_regid='$temp' ";
    $wpdb->query($upquery);
}

global $gcm_result;
$gcm_result = $inf;
return $inf;
}

function px_getIds() {
global $wpdb;
$px_table_name = $wpdb->prefix.'gcm_users';
$devices = array();
$sql = "SELECT gcm_regid FROM $px_table_name";
$res = $wpdb->get_results($sql);
if ($res != false) {
    foreach($res as $row){
        array_push($devices, $row->gcm_regid);
    }
}

return $devices;
}

function px_canonical($answer) {
$allIds = px_getIds();
$resId = array();
$errId = array();
$err = array();
$can = array();
global $wpdb;
$px_table_name = $wpdb->prefix.'gcm_users';

foreach($answer->results as $index=>$element) {
if(isset($element->registration_id)) {
 $resId[] = $index;
}
}

foreach($answer->results as $index=>$element){
if(isset($element->error)){
  $errId[] = $index;
}
}

if($resId != null) {
    for($i=0; $i<count($allIds); $i++) {
        array_push($can, $allIds[$resId[$i]]);
    }
}

if($errId != null) {
    for($i=0; $i<count($allIds); $i++) {
        array_push($err, $allIds[$errId[$i]]);
    }
}

if($err != null) {
for($i=0; $i < count($err); $i++){
    $s = $wpdb->query($wpdb->prepare("DELETE FROM $px_table_name WHERE gcm_regid=%s",$err[$i]));
}
} 
if($can != null) {
for($i=0; $i < count($can); $i++){
    $r = $wpdb->query($wpdb->prepare("DELETE FROM $px_table_name WHERE gcm_regid=%s",$can[$i]));
}
}
}

?>

via Chebli Mohamed