Hello Flavio,
Thank you for your message.
Unfortunately, right now you can only manually re-do your custom installation package even if you want to keep the same settings but update the installer's version. However, we already have a feature in our wishlist that would allow saving the configuration files themselves, i.e. it will be possible to go through the configuration process and only adjust some settings instead of setting them all from scratch. Unfortunately, there's no specific ETA on this feature yet.
Please let us know if you have other questions.