Drupal Form:want to show previous form value as default_value on page

Question

My Goal is if user is submitting this form with \"Product Name\" value as \"YYY\". On submit page should reload but this time \"Product Name\" should show previous valye as

Answer 1

I prefer to save all values in one time when we are speaking about complex forms :

foreach ($form_state['values'] as $form_state_key => $form_state_value) {
    $form_state['storage'][$form_state_key] = $form_state['values'][$form_state_value];
}