Please open the app, if you have auto updates enabled, you may get an option to upgrade or export your data. First, export your data, this will serve as a backup.
If you do not have auto updates turned on, open the app and export data. Then, try to update the app.
If you encounter any problems, please send a copy of the export file to
support@fuelly.com and I can load the data into a Fuelly account for you. Please set up a Fuelly account and let me know the year, make, model and submodel of your vehicles.