Regenerate attachment on the fly wordpress

regenrate.php

require_once( ABSPATH . 'wp-admin/includes/image.php' );

$img_id = get_post_thumbnail_id( $service->ID );
$parsed = parse_url( wp_get_attachment_url( $img_id ) );
$url = ABSPATH . dirname( $parsed [ 'path' ] ) . '/' . rawurlencode( basename( $parsed[ 'path' ] ) );
$url = str_replace('/', '/', $url);
$attach_data = wp_generate_attachment_metadata( $img_id, $url );
wp_update_attachment_metadata( $img_id, $attach_data );