Did you bring her back to the vet? Maybe she needs a stronger dose? I know that phenylpropanolamine sometimes takes a couple/few weeks to take full effect, did you give it long enough to see if it works?
Or even get a second opinion?

If all else fails is there anyway you can try to get her on a very strict schedule?
For example, keep her in her crate at night, then after she goes potty after waking up she may be able to be trusted to be free in the house for say maybe an hour. Then bring her back outside. then she'll be trusted in the house for another hour or so. Then crate her when you go out. etc... If she looks tired bring her out to potty before she gets a chance to potty in the house.
I know with this problem she'll never be 100% reliable but a strict schedule might help quite a bit. It will at least help with the amount of urine she leaks.