Keep it.
It's a good looking, reliable car. If you've had it five years, you must know it pretty well. IMO, it's definitely better to keep a car you know well than to take a gamble on another.
The only downside is the road tax. :(
I had an Astra estate which had 100,000 on the clock when I bought it - I did another 90,000 and started to get cold feet, because it was making a clunking noise. So I agreed a PX for something else, but the guy wanted me to get the clunking checked out before he took it. Turned out it was just an exhaust mount (cost about 5 quid). I really regretted selling changing it in the end...