Mirror Art is installed as an app and normally updates itself automatically. If it ever looks stuck on an old version — a button that's missing, or a fix that doesn't seem to have landed — use this to wipe the installed copy and pull a completely fresh one.
This clears the app's offline cache, unregisters its service worker, and resets any locally-saved settings (like whether you've dismissed the install hint). It does not touch any photos you've saved — those went to your device's normal downloads, not into the app itself.