if you don't want to lose the 9.5 revision especially if it’s the mainline you can create a branch from your mainline or the branch that you are working on and do the upgrade on it without effecting your current version, and it’s all depends on your strategy about the upgrade.
Nour is right. If you want to do it the easy way, you can also just open the existing project in the new Mendix Studio Pro locally. As long as you don’t commit it, nothing is lost. If it works as expected, you can commit, if not you can delete the project and check out the old version.