You can backup your data files at any time. Just click the "Backup" button under the tools menu.1
You can restore your data file backups at any time. Just click the "Restore" button under the tools menu, browse for the file and click restore.2
1It is recommended that you back up your data file to a separate drive on a weekly basis to prevent data loss from a system crash.
2WARNING This will overwrite the data file currently being used by DriverDiary. If you are unsure if you need the data that is currently being used, please backup the current datafile before restoring a previous backup.