Upgrading from one 9.2 image to the latest 9.2 image

Hi community,
I'm currently trying to answer a proposal for a project consisting in upgrading from 9.2 image 22 to 9.2 latest image. In my answer i need to describe the process of the upgrade focusing on how to retrieve and reapply the clients customization which are huge.
Can anyone help or have a document that could help me describe that process please?
Thanks a lot for your help
Osman