add_action('frm_display_form_action', 'check_entry_count', 8, 3);
function check_entry_count($params, $fields, $form){
global $user_ID;
remove_filter('frm_continue_to_new', '__return_false', 50);
if($form->id == 5 and !is_admin()){ //replace 5 with the ID of your form
$count = FrmEntry::getRecordCount("form_id=". $form->id ." AND user_id=".$user_ID);
if($count >= 2){ //change 2 to your entry limit
echo 'This form is closed';
add_filter('frm_continue_to_new', '__return_false', 50);
}
}
}