We had this issue, too. I think it's smart to allow her access to the potty. Since she's already older, I wouldn't want to stall that process any more, so I would not put the side back on, do pull-ups or anything else that could set her back.
We did the Super Nanny "stay in bed" technique and only had to do it twice, once for bed, once for a nap.
1. Go through bedtime routine (even for naps, we do stories, potty, etc) and put her in bed. Say, "it's bedtime, sweetie. I love you."
2. Leave the room. If she comes out, physically put her back in bed and say "bedtime". Do not honor requests for food, drink, etc.
3. If she gets out again, put her back and say NOTHING. Repeat as many times as necessary until she gets the message that she will be put back in bed EVERY time she gets out. It's bedtime and we stay in bed.
This worked for us as long as we went through the whole sleeptime routine before trying to put him down. One day, I sat outside his door reading. I saw him "checking" to see if I was there so he could get out. My presence was enough to keep him in bed. This was only for one day, then he stayed on his own.
She may be ready to give up naps. My son still naps, but even when he doesn't, he'll have quiet time in his room, so I still see this being useful.
Good luck on both counts!