What iOS version is your iPad running? Although updates do appear in the store for all apps, if the iOS on your iPad is not compatible with the app, when you go to update, it'll disappear. Or, you'll get a notice saying that the app cannot be updated.
So, you'll have to update your iOS to match the app version in order to get the new and improved app.
If your app says its compatible with the iOS you have running, then that's a different problem and, if I may ask - can you tell us exactly what is happening when you go to update the app?
Marilyn