Unless Arc is on a break (he was during holidays) the updates are every two weeks.
So 0.20.7 should be dropping on Monday, the 15th.
As for updating.
If you’re on android, download the APK for the new version and install it as an update. DO NOT uninstall, that’s how you lose your saves.
On computers it’s easier, just download the new version and launch, if your saves are there, you’re free to delete the old version.