It may be that you still have the old version of the app. In the past, we had a separate app for each language in the App Store and Google Play Store. It has never been our own choice but due to policy changes at Apple and Google, we were forced to move to one app and remove the rest of the apps from the App Store and Google Play Store. As a result, we can no longer update these apps (including yours).
As long as you have not removed the old app from your phone, you can still use it. The content in the app is still correct. Therefore, you do not need the new app for the information about the leaps.
If you would like to have the latest version with the new design and latest updates, you will have to buy it again.
Do you have the new app? Then you can check if your phone might be (too) full. Is your phone not (too) full? Then clear the cache of the appstore on your phone and restart your phone to try again.