This is an issue I am now dealing with again unfortunately. My 2 were fully trained in my other apartment but since I have moved there have been 2 incidences, one each, where they have weed outside the litter tray. I am putting it down to a change in their environment and finding their feet, but I am placing some of the blame on myself. Im going to add another litter tray, and Im now scooping the tray once it has been used, which if Im honest I used to avoid! Its not pleasant, but I think its helping.
Has anything changed for her recently? How many litter trays do you have? Have to say I do feel for you because I know from when mine were kittens how unpleasant it is have cat wee on your bed! Maasai weed on my legs once when he was little while I was sleeping! Uurgh!
Im learning where my two will and wont consider as a potential alternative litter tray too. Have you noticed any pattern? Here it is generally anything squishy underfoot, like clothes strewn on the bedroom floor, pillows etc. Its always in a defined area though, something on the floor for example, but never the floor itself (this was the same as kittens) so Im trying to avoid giving them the opportunity by removing anything I suspect they might consider using! My house is looking tidier as well....