I agree with LavyDunois' choice of an air cooler, but you need to consider fans, in general (even those on air coolers) don't last forever either. I'd say get a new closed-loop cooler before the warranty on your current cooler runs out.
This way, you always have one under warranty. Sell the old one because people are always looking for these in the used market. You should be able to get at least half the purchase price for a functioning closed-loop water cooler.
I personally haven't had a closed-loop cooler fail on me, but I've always replaced them prior to the warranty end date (and they've always been Corsair).