I'm assuming that you've had her vet-checked and she doesn't have an underlying cause for inappropriate urination (like a UTI)? If not, that's probably a good first step.
However, some dogs just take longer than others to house train. Our Cole took 8 months before if finally 'clicked'. Just stay consistent and she'll get it. If you catch her in the act, interrupt her (a throaty "uh-uh" worked for ours) and take her outside, then praise her when she finishes outside. Watch her like a hawk and learn her signals. She's likely giving some sign that she finds to be very obvious but which can be quite subtle to us mere humans!

Any time she goes outside and pees appropriately, she needs lots of praise.
What are you cleaning up the accidents with? An enzymatic cleanser formulated to neutralize urine is your best bet. If you don't eliminate the odor completely, she'll continue to pee in spots where she can smell old urine. Even if
you can't smell it, chances are
she can.
Good luck! It's hard to believe after all this time, but she
will get it eventually.

The good news is that it seems the longer they take to 'get it', the more solidly house-trained they are when they finally catch on!