Upgrade from 1.1.0 to 1.3.0

I am currently using version 1.1.0 and havve made some changes in the code and it works fine. I’d like to upgrade to 1.3.0 but dont want to have to redo the code changes as well as keep using the current data since it is a live site.

Any suggestions on how to do this?

I think upgrading will need some manual selecting and copy & paste as very much changed since 1.1.0