The fix will be to make small changes and observe how the car responds. That's something that not even the best advise or help on a forum can offer.

But if it helps:
My setups and those of Delves rely on the use of rounded pistons. If you're not doing this then our setups won't behave the same on your car. Also, our shocks are set up with low friction O-rings and the use of the emulsion style caps. We set our dampers up to have the least amount of internal stiction caused by the lower o-ring assembly - so as the o-rings swell over time, with each re-build, we make sure that the piston is still free to move and we back off the lower seal cartridge cap to the point whereby the shafts move most freely.

Without knowing the nature of the track you are racing on and the height of the jump landing you are grappling with, it's very difficult to do much more than offer guiding advice. If the car is landing onto a flat surface, you are asking the damper to do much more work than if you are down-siding the jump. If the surface is hard or hard packed, again, you are asking the damper to work harder to absorb all the jump energy than if the surface is softer.

So, for what it's worth. If the track is characterised by large jumps and landings onto flat surfaces, I would increase the pack of the damper and run a 5556 or a 5566 piston. This will mean that you will have to drill out the holes of the normal TLR pistons or get someone to make some pistons up for you. When I say 5566, that is a combination of a normal 4 hole 56 piston with to of the holes drilled out to a 55 size. Similarly, a 5556 means that you start with a 4 hole 56 piston and drill 3 of the holes out.

The difference that 1 hole makes in these big bore shock absorbers is noticeable and this is often how I will tune my car.
Don't forget though that as you increase pack, you will want to consider the effect that a 'stiffer' shock is going to have elsewhere around the lap. You will also want to alter the weight of your shock oil to help retain a balance of small bump activity and large jump impact absorption. The life of a simple damper is far from easy :-)

However, the most critical element to understand first is how much time the bounce is actually costing you overall. You might find that you will get a better overall lap time by accepting a bounce on one jump if the car remains stable and the overall set up is a better compromise throughout the rest of the lap. However, if the jump landing is causing you to crash and roll over, then it's time to change the setup so it works better on that feature.

For most of us, it's virtually impossible to get a perfectly set up car that reacts perfectly across the wide gamut of corners, features and surfaces that make up a single lap - so it's getting to a point where the car is consistent and the overall compromise is one that costs you the least amount of lost time.

Also, try also to consider what you are doing with the throttle at the point of landing. If you are on the throttle early (before the wheels have touched the ground) then you will be stiffening the entire suspension due to the power you re applying. If you're off the throttle, you'll allow the suspension to collapse more readily but perhaps you're then not getting on the throttle early enough to stiffen the suspension action and effectively 'help out' the damper.

Lastly don't under-estimate the effect that Anti-Squat has on both the suspension movement on and off power and also the jump arc the car will carry in the air. If you are running more anti-squat, you will jump higher over any given jump and so your car has more energy to absorb on landing. Again, Delves and my setups are currently using 2 degrees of anti-squat - if we changed the Anti-squat to alter a characteristic, I wouldn't be surprised if it then had a knock on effect (either good or bad) to other areas of the car's handling/ Remember, we often make a change and consider the positive effects that the change will have. The very best guys are those that also consider the negative effect that the change will impart. Its a yin and a yang thing :-)