Naomi, I'm sorry to hear that Bassett is having peeing problems again.
Since she pees outside of the litter box, have you ever tried putting some puppy training pads down around the litter box? They're supposed to be scented so they attract the animal to them. I use them behind my covered litter boxes because my furkids spray in the corner of them and it leaks through. This way it only leaks onto the pad and it absorbs the pee. Good luck and please keep us updated.