how do I retrieve app info from icloud

I have an iPad Pro 12.9 inch Gen 2. All updates are current.

I had a problem with an app. I contacted the games website and they advised of the steps to take. This involved backing up my ipad (yes, the game was switched on to being saved), deleting the app, turning off the ipad and re-installing the app, then recovering all my data.

I did all this. The app re-installed correctly, and all my puzzle packs were successfully re-uploaded. However, none of my previous game history (which included hundreds of puzzles and challenges) were restored.

I contacted the company again, who said they couldn't help, only with the actual puzzle packs (which were successfully restored). They said any game progress data would be saved through the iCloud backup, which I had done just before deleting.

So, through Apple iCloud, how do I retrieve the info from this one App please? It's years of work and I really don't want to have lost it.

Thanks in advance :)