I'm in the same position and do a couple of things that I've found useful. I used to clean out the lofts twice a day boxes and floors but then of course the back goes and they weren’t getting cleaned out at all, the environment within the loft changed dramatically which knocked the pigeons back. To sort of semi combat this I put Easibed down on the floors and just cleaned the boxes/perches once every two days, I found the transition wasn't as harsh as it became a more stable environment for the pigeons.
The other is to race the old birds on widowhood, much easier to bring these into condition than naturals after a spell of being laid up.