We don't store your data, period.
Any settings or data from refuel are stored only on your device/iCloud backup, neither of which we have any access to.
Refuel uses your iCloud account to securely back-up your data, we have no access to this. This is stored so if you delete the app, you don't lose all your data. You can disable iCloud app backup if you want.
If you're interested, here's our website privacy policy.