re-catcha / zend / javascript question

Question

I generate a recaptcha box on a form like this.

<?php    
    $recaptcha = new Zend_Service_ReCaptcha("key", "key");   
    echo $recaptcha->getHTML();    
?>

and perform form validation using javascript. I would like to change the captcha phrase each time user unsuccessfully submits form. Can this be done using javascript?

thanks