Oh you poor thing! It sounds as if she's got well and truly used to sleeping upstairs and is finding the adjustment very hard. You probably should ignore her, but this is easier-said-than-done - especially if you have neighbours! If you don't have neighbours I'd put in ear-pugs and try to ignore her. Does she need to wee or poo in the night too? Maybe you need to start from scratch and set your alarm every few hours to take her out? Oh, the sleep deprivation must be driving you crazy
I would recommend trying to play with and train her a lot in the evening so that she is knackered. You may well already be doing this, but maybe she just needs even more play time.
I assume she's also teething, so could be in some kind of discomfort. Has she lost any teeth yet? Some people have recommended some gel to sooth their gums. Henry is chewing a lot on a piece of a cardboard box - seems to soothe his teething quite well (although he doesn't have problems at night).
Good luck!