D.A.
My daughter is the same age and we have been having the same trouble.
I did put a gate on her door since our bedrooms are on the 2nd floor (Long story, but due to way staircase built, we couldn't get the gate on top of stair.) Anyway, I remembered one of the "Super Nanny" episodes that I watched so diligently when I was pregnant. (LO) Her advice was to put the child to bed as normal and let them know your expection to stay in bed. The first time they get up, bring the child back to bed and say it's bed time. Any time after that, go into the room and put the child back to bed. However, say NOTHING. I swear it is working for me. I am astonished. I just point to her bed, climb over the gate, tuck her in and leave. The whole time she tries to get me to talk to her. In her mind, my talking to her is the reward. If the child is not getting the reward, then she has no reason to continue. I am still having to go into her room about two times, after the initial bedtime. Considering the recent past, that's nothing. We only switched to this silent thing about two weeks ago.
In our case ,I think the delay of a complete solution is due to inconsistancy. When I'm not home, my husband has a hard time staying quiet. He's a big sucker. :)
However, he does see that that when he puts my daughter to bed it's a very long ordeal. When I'm home & put her to bed, no problems. I think he'll catch on soon.
I do think you have a good idea to continue to reward the next day, when you have a good bed time. I think I'm going to try that. Maybe her favorite special breakfast the next morning with lots of compliments on her prior nights bed time behavior.
Good luck!!!