Since she is using the portable potty maybe you could slowly move it back towards the bathroom. I had to do this with a student of mine once before and what we did was just moved the portable potty about 1 foot every couple of days. Eventually the portable potty was back into the bathroom beside the toilet and we were able to transition the child back to the potty.

With the child I had to do this with, we found out after the fact there was a repeated noise in the bathroom which is why he stopped using it. We explained the noise, water in the pipes and everything was OK once we transitioned him back into the bathroom.

I had been doing the rewards for her using the potty but she's never been very responsive to the reward system--oftentimes she will decline a reward. I did end up putting a portable training potty in her room today and I went over what she needs to do to clean up every time she chooses to use that potty instead of the big potty in the bathroom (i.e. carry the bowl to the bathroom, pour the #1 or #2 into the big potty, wipe the potty seat if it splashes, flush the big potty, rinse out the portable potty bowl in the tub (don't worry, I clean the tub with Comet before every bath lol), put it back in the portable potty in her room, and wash her hands. You would think that would deter her but no! She's already used it twice! However, she cleaned up perfectly (with my supervision but very little assistance) and there's no pee on her floor so it's a good start! :)

I am new to this so forgive me if my answer seems strange or stupid. I wonder if you tried putting a little portable training potty in her room where the problem is. Then have her dump the urine in the toilet so she knows thats where it goes. Maybe it is just a way for her to get her own way? I know my son hated to use the bathroom anywhere but home. He also wouldn't go #2 because he thought the toilet would get him. Yet was fine to urinate.?? Then I had a daughter that everywhere we went she had to check out the bathroom. You never know what they are thinking? We just have to figure out the way to change behavior. Maybe she will get sick of cleaning out her little bucket? It's not ideal but maybe better than pull ups?

We've purchased a Hoover Carpet Cleaner. It's worth the expense. We also purchase the Pet Oder Removal, Nature's Miracle. We constantly use both. We've worn out one cleaner already. But so worth it to have a hand. It's just important to try to catch the accidents when they happen and not let urine stand for a period of time. Though, sometimes it's hard to get an answer out of our child and we end up cleaning a larger area than we didn't need to do.
Good luck! It's an ongoing issue for us.

I think Tanji has a really innovative idea.

Another idea is to do over-correction and reward. Overcorrection is having the consequence be a bit more extreme than a natural consequence. So you have her clean it up and also have her clean it and clean it and clean it some more. Really get the idea to sink in. And during the same time period, reward her each time she goes on the toliet with a small piece of candy or popcorn or something.