One thing to note is that you know everything about this car already. You know whether it fits your lifestyle, whether you like the amount of space, how it handles turns, how it brakes, etc...
More importantly, you know its service history, quirks, how it was handled the past 2 years, etc...
Turning it in and buying another different used car introduces uncertainty. You can mitigate a lot of that incertainty by looking at past service records, getting it inspected, and taking test drives, but there's still no guarantee that you're not getting someone else's mistreated lemon of a car.
Excluding your financial situation (whatever it is - you don't mention), If the residual value is somewhat near or less than the KBB buy value of an equivalent car, I'd keep the one you have if you're happy with it.
Ricksun