How to change form submit button value after form submission? I want to change the value of the submit button after the the form is submitted successfully without any validation errors.

And then when the page is reloaded the button's value will be changed to its original value?

I think its not possible with any javascript or jquery but I can't find a value in the $form_state array to set a js variable.

Edit:
The form is submitted without ajax. The button should be replaced with that text after the form is submitted. And then when the user comes back to page again or reload it again then the text should be reverted.
You can do this with two steps. The first is to check whether $form_state['values'] has been set, and change the value accordingly:

if(!isset($form_state['values'])) {
  $form['submit'] = array (
    '#type' =&gt; 'submit',
    '#value' =&gt; t('Submit'),
  );
}
else {
  $form['submit'] = array (
    '#type' =&gt; 'submit',
    '#value' =&gt; t('Submit Again'),
  );
}


The next step is in your submit function, where you have to tell Drupal to rebuild the form (rather than build it from scratch)

$form_state['rebuild'] = TRUE;