I would put her in a small area (like a large dog kennel or a bathroom) like your friend suggested. Keep the litterbox very clean continue to use the cat attract and the feliway wouldn't hurt either. Basically re-train her that her litterbox is the place to go. If you are not up to that then I would put several litterboxes through out the house where she is inclined to pee, if it is not in a good spot to put a litterbox then lay down a section of aluminum foil over that spot (tape the corners so it stays in that spot and is not easily moved) and have a litterbox close to that area.