vBulletin has a standard redirect you could use, however it is not equivalent to the back button. Using this method, you will loose the values your user previously set unless you forward them into the next page:
PHP Code:
$url = "http://www.yoursiteurl.com/yourscript.php";
standard_redirect("Redirect Message.",$url);
You might instead choose to use JavaScript to validate the form and pop up an alert if the title box is empty.