How to reinstall or change frappe?

In my server, I have frappe installed in bench.
But after doing changes to it, I want to reinstall frappe to get a fresh frappe as in repo.

I don’t want to do bench reinstall because I have data on the site.

How do I do it?

If I rename the source repo (after forking to my github), the bench get-app will only clone it with the new name but not install it.