First, make a backup of your database.
You do not need to "buy" a new copy. You can simply download the program from the DVDP site and install it. You will need to know the name you used when you registered originally, and you'll need your registration key. If you don't know what it is, you can go on the DVDP website and click on 'Registration>My Registrations' and it will be displayed for you.
Once you've installed the software, just do a "Restore" of the backup file you created previously.