WordPress - Redirect a page using a filter

functions.php

//Redirect a page using a filter
add_filter('get_the_permalink','my_permalink_redirect');
function my_permalink_redirect($permalink) {
    global $post;
    if ($post->ID == your_post_id_here) { //Page ID you want to redirect
        $permalink = 'http://new-url.com/pagename'; //Redirect destination page
    }
    return $permalink;
}