[Carina]

FIRST thing is to take a urine sample in to your vet, just to rule out a urinary tract infection. These are quite common, and may well be the case if she was fine in her crate and then relapsed. Is she spayed? UTIs are more common in spayed females.

It could be that she does pee when there's no towel in there, then "cleans" it up, or lies in it so it dries or it evaporates. If there's no UTI, and she does indeed pee only when her towel is there, maybe finding an alternative to a towel (perhaps she smells the urine on it, even after its been washed) or getting her used to no towel will work. One of my dogs generally refuses to lie on a dog bed, he actually prefers a cool, hard surface. Being young, it really won't hurt her.

Do check for a UTI, though. Sometimes those can be painful, and then you'd know for sure whether you're dealing with a medical problem (easily cured) or a behavioural problem.