Zend form parameters - how to change after instanciated

I have a form that I need to resubmit to the action if a checkbox is TRUE. This is to facilitate chained select boxes with javascript turned off. Ideally I would instanciate the form object at the end only, just before sending it to the view, but as you can see I need it beforehand.

The form takes parameters (an array of lists used to populate the select boxes), and these parameters are not yet calculated at the point where I have to first instanciate the form object. Is there a way to instantiate the form and add the parameters later, thus avoiding having to re-instanciate the form at the end when I have the definitive lists?

Can anyone see a better way of doing this?

public function editcontactdetailsAction() {

        $auth = Zend_Auth::getInstance();
        $id = $auth->getidentity();
        $user = $this->em->getRepository('Entities\User')
                ->findOneByid($id);
        $town = $user->getTown();


        // initialize list values as null
        $townlist = array();
        $provincelist= array();
        $regionlist=array();
        $countrylist=array();
        //initialize ids as 0 so defaults can be set
        $townid=0;
        $provinceid=0;
        $regionid=0;
        $countryid=0;
        //initialize $data variable used to set defaults later
        $data=null;

        // HAS town - get corresponding lists for dropdowns
        if (!is_null($town)) {
            $townid = $town->getId();

            //get the province
            $province = $town->getProvince();
            $provinceid = $province->getId();

            //get the region
            $region = $province->getRegion();
            $regionid = $region->getId();

            //get the country
            $country = $region->getCountry();
            $countryid = $country->getId();

            $townlist = $this->em->getRepository('Entities\Town')->findActiveTowns($provinceid);
            $provincelist = $this->em->getRepository('Entities\Province')->findActiveProvinces($regionid);
            $regionlist = $this->em->getRepository('Entities\Region')->findActiveRegions($countryid);
        }

        // even if user NO town, populate the countries list
        $countrylist = $this->em->getRepository('Entities\Country')->findActiveCountries();

        $lists = array($townlist, $provincelist, $regionlist, $countrylist);
        $form = new Application_Model_FormContactDetails($lists);


// 
//---------------------------------------------------------------
        // Has the form been submitted?
        if ($this->getRequest()->isPost()) {
           //if we dont include the $validformline, the form is not populated with the post data
            $validform =$form->isValid($this->_request->getPost());
            //Is this a request to refresh the regional structure and not a real submit
            if($form->getValue('refreshregionalstructure')==1){
                //find out up to what the level the user has selected, starting from the bottom
                $formprovincevalue=$form->getValue('province');
                if(!$formprovincevalue==0){
                    $townlist = $this->em->getRepository('Entities\Town')->findActiveTowns($formprovincevalue);

                }

            }
            else{

            // If the form data is valid, process it
            if ($form->isValid($this->_request->getPost())) {


                //save all to db
                try {

                    // Save the user to the database

                    // Set the flash message
                    $this->_helper->flashMessenger->addMessage(array('success' =>
                        _('The contact details were updated')));


                    // Redirect the user to the home page
                    $this->_redirect('/account/index');
                } catch (Exception $e) {
                    $this->em->close();
                    $this->view->errors = array(array(_('There was a problem editing your contact details.')));
                }
            } else {
                $this->view->errors = $form->getErrors();
            }
            }
        } else { //form has not been submitted yet
            // populate form with user record
            $data = array('firstname' => $user->getFirstname(), 'middlename' => $user->getMiddlename(),
                'surname' => $user->getSurname(), 'address1' => $user->getAddress1(),
                'address2' => $user->getAddress2(),'town'=> $townid,
                'province'=> $provinceid,'region'=> $regionid,'country'=> $countryid);

        }
        $lists = array($townlist, $provincelist, $regionlist, $countrylist);

        $form = new Application_Model_FormContactDetails($lists);
        //if we dont include the $validform line, the form is not populated with the post data
        $validform =$form->isValid($this->_request->getPost());
        if (!is_null($data))$form->setDefaults($data);
        $this->view->form = $form;
    }