Re-covered or put new foam in your seat cushions?

You have to be careful not to make the overall height of the bottom cushion taller because it has to fit under the back cushion that has limits of the top rail.

I found when they get tired is to simply put a layer of a cushion material 'under' the existing cushion. Less expensive, does the job and you can add as much as what will fit. And replacement is just as easy.