Sorry to hear your cat's having some problems. There are a variety of reasons cats urinate in inappropriate places (such as on their owners). It's worth a vet checkup if she hasn't been in recently. If it's senility there's probably not much to be done, but if aging is causing her stress because she can't see and hear as well and is afraid, you might be able to make her more comfortable by using
Feliway. It's a synthetic version of the pheromone cats leave behind when they cheek-mark objects, and makes cats feel more calm. I used it recently when my cat got idiopathic cystitis (triggered by stress) and had to be hospitalized.
An enzymatic cleaner such as Nature's Miracle can clean up the spots where she's gone outside the box so the odor doesn't attract her to that place again.