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.

Mithilfe von panels_get_current_page_display() kann man das aktuelle Display in der preprocess_page laden.