retain the values of a registration page after captcha mismatch

After captcha mismatch, how to fill/retain the values of a registration page?
Controller code is

Code:

if (!$captcha_text_matched) {
               $this->session->set_flashdata(
                       'register_message', 'The entered text is not matched.'
               );
               redirect(base_url('user/register'));
           }