A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
Dear Jeff,
Welcome to the forum here and I'm very sorry to hear the data loss issue in your environment.
Please first check whether you have backed up the data with iTunes, with iCloud Backup or on iCloud Drive. If you have backed up the data through one of the three ways previously, you may try checking whether you can get the data back at your side.
If the data is only stored on iPad, I suggest you check whether you enable AutoSave on File. If no, the issue may happen and I'm afraid that the data may be unable to be got back in your environment.
For better way to get rid of the data loss in the future, I kindly suggest you save the Excel files in the OneDrive for Business site or the SharePoint Online sites. After you save them there, AutoSave will be enabled automatically and you can find the version history from any other devices if some data loss issues happen and then you may be able to recover the data from the version history at your side.
What is AutoSave? (microsoft.com)
View the version history of an item or file in a list or library (microsoft.com)
Thanks for your understanding and have a nice day!
Sincerely,
Cliff | Microsoft Community Moderator