I'm assuming this is voluntary, and not involuntary leakage or a UTI? If it's involuntary after spaying you can give her phenylpropanolamine syrup. If it's voluntary I would spay her to start with if she isn't spayed.
I read this on the net and it makes sense:
The solution is to start over again as if she is an 8 week old puppy and train her.
Do not let her loose in the house, at all right now.This retraining period may take several weeks. During this time, get your carpets cleaned. Do not give her access to the carpets. Confine her in a crate or in a small room with a hard floor. Give her freedom in the house only in small steps.
Other ways:
Watch her intensely for a couple a weeks.You can either try a collar that sprays her with an unpleasant substance with a remote control that you activate if you catch her in the act . Or fill a can with coins and shake it when she starts to pee.