function blank_month_and_year_pmpro_checkout_before_submit_button()
{
	echo "
	<script>
		jQuery('#ExpirationMonth').val('');
		jQuery('#ExpirationYear').val('');

	</script>";
}

add_action('pmpro_checkout_before_submit_button', 'blank_month_and_year_pmpro_checkout_before_submit_button');