App says I need to buy it

A few days ago I tried to open my gospel library app and I got this message: “This app is no longer shared with you. To use it, you must buy it from the App Store.” I hate to delete my app and reinstall because I have a lot of data saved that I don’t want to lose. Any ideas how to fix it?

See the "App is no longer shared with you" error thread for more information.