New springs will probably do the trick, but you should do all of them.
Be sure that you also have "gas" shocks on the car. The removal on these shocks or if they are old is simlar to 75 lbs a piece. All four add up to the equivalent of a three hundred pound person hopping on.
Each spring is also mounted in a rubber pad. These can be changed to increase height. Its a lot of work so springs are probably the surest tactic.
Bosch Master, ASE Master, L1
33 years MB technician