Unfortunately a character who changes appearance would result in massive file bloat, not to mention a horrendous amount of work for me, as I'd need to render out each variation combination manually (and as a solo dev, that would be rough! :P ) but I'm working on something for the next game that might allow for that kind of thing.
You can either update the game manually or via the Itch app, depending on preference and OS.
PC, Mac & Linux: Either use the Itch app, or download the entire update and extract to a fresh folder. Then play!
Android: Itch app doesn't work for updating so you have to manually download. Install the new APK on top of the old version (DO NOT UNINSTALL THE GAME!)
Whatever method you use, the save files will be automatically transferred between each version :)