There is no single button automated upgrade in Peppermint (and possibly never will be), we consider them risky and unsupportable. They also encourage a lax attitude towards consideration and backup of data that is important to the user .. automated upgrades DO go wrong (it's inevitable), and we'd rather promote the backup of important data necessary in a re-install.
Also, because of the way Peppermint uses cherry picked components from many DE's, there's a good chance that between versions we'd make changes that would make an automated backup impossible without entering the users /home and changing/deleting some config files .. we don't consider this our domain in any way shape or form.
Okay now I've explained that, we have recently (and where possible) decided to publish MANUAL upgrade instructions, where the user can decide for themselves if they want to:-
https://forum.peppermintos.com/index.php/topic,8442.0.htmlIt won't ALWAYS be possible to do this, but we will where we can.