Change the springs and shocks on the suspension is the easy way. There are loads of kits around that will do this, get one of the Land Rover mags and have scroll through. Basic cost, you're looking around £200 for the parts if you do the job yourself, which is quite easy.
You can get spacers that go under the springs so you use the original ones but if the springs are worn and it can make the ride very unstable, the shocks will be too short and basicly the springs will not be rated correctly.
