You might want to consider an uncovered litter box as well. Even though she used one before, her preference might have changed. I know an uncovered box isn't exactly attractive but because a covered box can hold in moisture and bacteria it can cause a really foul odor in the box.

Do you have enough litter boxes? Sometimes a kitten needs a few more than an adult cat. I had an extra box for awhile because Ava couldn't make it to the one across the house.

I would also check with your vet. Maybe she has a urinary tract infection or something which would cause she to urinate outside of the box.

Hope that helps.

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