Pushing an update to Google Play that will replace the existing app

Question

I have an app that is currently on the Play Store, and I would like to publish an update that will replace the existing app with another app that is an improved version of t

Answer 1

If they share the same unique key, you can overwrite the existing app with the new one. It doesn't make any difference how much it's changed. Play will automatically take care of notifying exising users of updates, and depending on their settings, update them automatically.

If your new version does NOT share the same unique key, you have no choice but to put up a new app.