1) Sell your old computer while you can still get something for it. The older it gets, the less it's going to be worth.
2) Buy another Uwatec computer (another Prime, or the Tech2G if you want an upgrade that has gauge mode and depth averaging) as primary or backup (whichever computer is better as primary). Consider carrying both computers on all dives, if you're doing multiple dives per day, so if one fails you can pick up right where you left off, with a computer that still tracks the correct amount of nitrogen loading.
Now you're set.
2) Buy another Uwatec computer (another Prime, or the Tech2G if you want an upgrade that has gauge mode and depth averaging) as primary or backup (whichever computer is better as primary). Consider carrying both computers on all dives, if you're doing multiple dives per day, so if one fails you can pick up right where you left off, with a computer that still tracks the correct amount of nitrogen loading.
Now you're set.