What lift kit are you considering?
If all your ball joints and everything are in good shape, you shouldn't have a problem. The only thing you might worry about is the rear driveshaft. Some late-model XJs will vibrate with only a small lift. IF this happens, your options are to either lower the transfer case, or install a slip yoke eliminator and CV driveshaft.
The transfer-case drop is cheap and easy, and works for most people who use it. You'll spend less than 20 bucks. the drawback is that it lowers the entire transmission crossmember about an inch, so you lose that much ground clearance. for this reason a lot of off-roaders don't like this kind of fix, but if you're not off road all the time it can be practical.
The SYE, on the other hand, won't kill your ground clearance, but you'll pay a whole lot for it. at 2", you may very well pay more for that than for the lift. this replaces the output on the transfer case with a fixed yoke, and allows you to use a CV driveshaft, like is used in the front. this is the best way to fix vibrations.
with some luck you won't need either, or can get away with the TC drop. but all XJs respond differently to being lifted. I have 3" and no vibrations with stock driveshaft and no TC drop, but it's an older XJ. you'll just have to put on the lift and see what happens.
aside from that you shouldn't NEED anything. An adjustable tracbar will keep the axle perfectly centered, but at 2", it may not be off much after lifting. if your swaybar hits the coil springs, you can buy extended links or make some. longer shocks will make it ride better on/off-road, but are not completely nessesary with 2" unless you're looking for maximum flex or a perfect ride.
one thing to remember is ALWAYS get an alignment done after lifting, or your tires will wear quickly.