How to add excerpt_more filter to this Excerpt code Wordpress (ok)

if ( ! function_exists( 'custom_wp_trim_excerpt' ) )
{
    function custom_wp_trim_excerpt($excerpt) 
    {
        global $post;
        $raw_excerpt = $excerpt;
        if ( $excerpt == '' ) 
        {
            $excerpt = get_the_content('');
            $excerpt = strip_shortcodes( $excerpt );
            $excerpt = apply_filters('the_content', $excerpt);
            $excerpt = substr( $excerpt, 0, strpos( $excerpt, '</p>' ) + 4 );

            $excerpt_readmore = ' &raquo; <a href="'. esc_url( get_permalink() ) . '">Read More</a>';
            $excerpt_more = apply_filters('excerpt_more', ' ' . $excerpt_readmore);

            $pos = strrpos($excerpt, '</');
            if ($pos !== false)
                $excerpt = substr_replace($excerpt, $excerpt_readmore, $pos, 0);
            else
                $excerpt .= $excerpt_readmore;

                return $excerpt;
        }
        return apply_filters('custom_wp_trim_excerpt', $excerpt, $raw_excerpt);
    }
}
remove_filter('get_the_excerpt', 'wp_trim_excerpt');
add_filter('get_the_excerpt', 'custom_wp_trim_excerpt');