Yes, you may re-migrate your data. It looks like you migrated in March 23, but I did not see a backup file to check the data.
If you haven't deleted the app, the backup data should still be in the app. Or, if you have the email with the backup data link, you may use that. This link shows the steps need to do this:
Upgrade Troubleshooting - Missing Data
Prior to doing that, I would go to your Fuelly profile and Export Fuel-ups from March 23 to now. It looks like 3 fuelups. The re-migration will delete the data in Fuelly and replace it with the data from March 23. You may then Import Fuel-ups and import the previously saved export.