Crate her. Buy her a nice crate, lots of fluffy blankets, and that's her new bedroom at night. When dogs have a larger area its easier for them to wander off and relieve themselves instead of holding it in. If she does pee the blankets you will know she didn't mean to and can easily wash the blankets each week.
You can also get her a diaper to wear at night only, for when you put her to bed in the crate. Don't buy those expensive doggy wee diapers though, use women's sanitary pads, super cheap brand, and slip them in the cloth diaper holder instead.
Hope this helps, dogs really do like their own den once they are introduced to it in a positive manner. Lots of treats! Lots of blankies! Best wishes from a fellow dog lover.
---- Just wanted to add that if you don't want to pick up the water bowl, block it with a large cardboard box over the top of it. If necessary, if she tries to push the box up, place books on top of the box for added weight. Also, for training her out of the "sneak off and pee" mode, you can attach a leash to her and have the handle under the sofa leg. Leave the leash attached to sofa leg at all times, discreetly hide the leash under the sofa when not in use or if you have company over, but when you are just watching tv attach her to the leash. She can lay at your feet, have your attention, but cannot sneak off. I had to do this with my Lhasa when she was young.