Are you wanting to reset the Land Rover Discovery 3 Suspension, this is a very common issue with these vehicles, possible solutions include taking your vehicle to the shop (garage) for the dealer to take a look at this problem, another less expensive route may be to download a Landrover Discovery 3 Repair Manual, by downloading this manual you will future proof all possible problems that may arise.
On the suspension faults it might be beneficial to pay attention to the compressor. Is it louder, running longer that you notice. It may be starving for air.