Today I learned the hard way that losing your app's key store means no more updating , bug fixing , performance boosting , features adding ...
The app had like 5k downloads on the play store ..
Lost the key when one of my hard drives burned ..
Lesson of the day : keep your keys safe .
*trying to stay strong*

Good luck man, hope it works out

If you have a way in your app to force an error message from an API call (you actually use the error message on some API response to show a pop up or something) you can use a workaround a friend used. Create a "PRO", "PLUS" or "++" version with a new key and some extra feature(s). Once you have it working you can force an error on some unimportant calls that tells the user "Install our new app for free!". It's better if it's some kind of call that doesn't really bother the flow of your existing app. He used a call that was made once a day on background to check the status of some cached data. It's not "nice" but he eventually got most of his users back on board.

@Eariel it's actually a really good idea , i'll definitely try it once I'm home , thank you.