Work with the corner she has already chosen
An older rabbit who has used one corner for months has done the hardest part of litter training for you: she has picked her toilet. The mistake is insisting the box go somewhere tidier. Put a large, low-sided litter box in that exact corner — older rabbits, especially stiff ones, need an entry side low enough to hop over comfortably — and you are converting an established habit rather than building one from nothing. Expect scattered droppings elsewhere at first; those are territory markers, while the puddles and the main pile are what the box is for.
Set the box up the way rabbits actually use one
Line the box with paper-based litter and cover it generously with hay, positioned so she sits in the hay while she eats it — rabbits naturally graze and toilet at the same time, and a box without hay often fails for exactly that reason. Avoid clay and clumping litters, which are unsafe if nibbled. Place a hay rack or second pile at the box's end if she is a keen eater. Sweep any droppings you find outside the box into it for the first weeks, so scent keeps confirming the box as the toilet, and clean urine accidents elsewhere promptly with a pet-safe cleaner to erase the rival signpost.
Shrink the world, then give it back slowly
Temporarily pen her living area down around the chosen corner — a pen enclosing the box, her water, hay and a resting spot — so every toilet urge happens within a short hop of the box. An older rabbit with a whole room will keep some old habits alive simply through distance and routine. After a week or so of reliable box use in the pen, expand the space in stages: a little more room every few days, with a second box added if the expanded area is large. If accidents restart, step back one stage rather than starting over; her corner habit is months old and unlearning takes a few weeks, not days.
Comfort details for an older body
Everything about the setup should respect an older rabbit's joints and habits. Shredded paper or hay over the litter softens the landing, the box should sit somewhere she already passes often, and the pen stage should include her favourite resting mat so the smaller world still feels like home. Watch how she enters the box: hesitating at the side or scrabbling suggests the entry is still too high, and cutting one side down lower usually fixes use more honestly than more training. Small comforts like these are often the difference between a habit that sticks and one that fades.
When it is not a training problem at all
A change or persistence in toileting habits in an older rabbit deserves a health thought as well as a training plan: stiffness can make a high-sided box genuinely hard to enter, and rabbits who suddenly cannot hold on or who strain should be seen by a vet rather than retrained. Watch that she is eating, moving and producing normal droppings through the retraining period. Putting the daily box changes and each space expansion on the rota in KinsLe's Care Teams keeps the stages consistent between everyone who cares for her, with each completed clean-out marked so the routine never slips.