The plugin should have an option to reverse a partial or full redemption to put the amount back on the voucher.
We’d just like to let you know that the addon for reverse redemption is available now.
You can purchase it from here: https://codecanyon.net/item/woocommerce-pdf-vouchers-reverse-redemption-addon/24195508
Read more here: https://docs.wpwebelite.com/woocommerce-pdf-vouchers-addons/reverse-redemption/
We will implement this feature in upcoming update. 🙂