After Christmas many users seem to upgrade their devices and of course want to transfer the data on Tennis Math installed on the new device.
As for the current version 2.2.5 there is unfortunately no true mechanism to backup and restore the database.
We are now working on the next major version 3.0, where besides of other very cool features you will be able to upload your matches to the central server storage, distribute it on multiple devices and of course share with friends!
So for those users who face now with the issue of upgrading their device and want to keep your valuable data, we can offer two possible temporary solutions:
1) keep your data on your old device. As soon as we release the version 3.0 you will be able to create an account, log in to the server and upload the matches from both your devices to the account.
2) if out of some reason you can't keep your old device, please send us your database dump (Menu -> Feedback -> Send DB to developers) with a short remark like "DB dump for merge into 3.0". As soon as we launch the 3.0 and you create an account we will manually merge that old data in.
We apologize for any inconveniences.