function clear_form_elements(ele) {

    $(ele).find(':input').each(function() {
        switch(this.type) {
            case 'password':
            case 'select-multiple':
            case 'select-one':
            case 'text':
            case 'textarea':
                $(this).val('');
                break;
            case 'checkbox':
            case 'radio':
                this.checked = false;
        }
    });

}

That said, we often don't want to clear a form – we want to reset it. This is how:

document.forms['myFormName'].reset();

$("#postform").submit(function() {
var ser = $(this).serialize();  //produced above response
$.post($(this).attr("action"), 
          ser, 
          function(response)
          {
          $("#results").html(response);
       });
});