I'll assume you're playing on Android since only Android users seem to have issue with this.
In order for Android to properly register the installation of the new build, you first have to completely uninstall the previous build. This is a quirk of the Ren'py engine that I have no control over, unfortunately.
There's also a good chance you'll lose your save data doing this. I recommend backing them up beforehand. They can be found on most Android devices in the "Data" folder of its storage section.