I'd keep it....but with a twist...
I read a letter in EVO magazine once where a bloke had a Jag XK8 (I think but it doesn't matter what car I suppose). He had gone into the Jag dealers to get a newer Jag but the money they'd give him for a trade in was pitiful.
As he loved the car anyway he got some advice from a Jag specialist on how to freshen it up a bit. He didn't "tart it up" as such, just improved it. New uprated suspension (no idea if lowered), better brakes, new tyres, full service and tune of the engine with a couple of extra performance bit (exhaust to improve airflow and to make a better engine note, filter/plugs etc). Add on a full pro valet with mopped and polished/waxed paintwork to make it look brand new.
He ended up with the car he really wanted - the one he already had but better - all at a fraction of what buying a newer model would have cost.
The other advantage is that you know your car's history, you're not taking a chance on another performance car which may well have been thrashed to bits or poorly maintained.