Since version 1.7 of ctools there is a new js api to auto-submit certain form elements.
Everytime a user changes a selectfield or inputs something into a textfield a button will be clicked automatically by js.

It's really easy to implement for your form:

• First you need to add the js
  
     // Add ctools specific js.
      ctools_add_js('auto-submit');
• Assign the autosubmit for a certain button:
  
      // Add autosubmit button.
      $form['submit']['#attributes']['class'] = $form['submit']['#attributes']['class'] ? $form['submit']['#attributes']['class'] . ' ctools-use-ajax ctools-auto-submit-click' : 'ctools-use-ajax ctools-auto-submit-click';
• Autosubmit every element in a form(there is a patch for it.)
  
      // Add classes to every form element.
      $form['#attributes']['class'] = $form['#attributes']['class'] ? $form['#attributes']['class'] . ' ctools-auto-submit-full-form': 'ctools-auto-submit-full-form';
• Autosubmit a single form element:
  
  $form['foo']['#attributes']['class'] = 'ctools-auto-submit';

As a result you could for example implement this for every exposed form of a view, see http://github.com/dereine/Views-autosubmit-exposed_form

This was initial developed for ctools export-ui goodness.