How to Refresh the List in suitelet on field change

i have created a suitelet. I want to refresh my list when a field is changed on the suitelet.

below is the code for the suitelet:
function suitelet(request, response){
if ( request.getMethod() == 'GET' )
    {
 
  var form = nlapiCreateForm('First Form');
  form.setTitle('My Test Suitelet');
  form.addField('email','email','Email');
 
  form.addField('employee','select','Employee','employee');
  form.setScript('customscript311');
  var contacts = form.addSubList('custpage_contacts', 'list', 'Custom Contacts', 'general');
  contacts.addField('custpage_checkbox', 'checkbox');
  contacts.addField('email', 'email', 'Email');
  contacts.addField('firstname','text','Name');
 
 
  if(nlapiGetFieldValue('employee')== null || nlapiGetFieldValue('employee')==''){
  var columns = new Array;
  columns[0]= new nlobjSearchColumn('email');
  columns[0]= new nlobjSearchColumn('firstname');