Hi A.,
As the your daughter grows & develops she will change her behaviors to figure out her boundaries, (what she can get away with). That is what she's doing now. I know how you felt the first time she did it, as it was not her usual behavior. Once you realized she was not sick you needed to re-establish the routine.
A good bedtime routine helps her learn to calm down for sleep, which it sounds like you have. To help prepare her for bed also tell her it's time to go to sleep, or whatever you words you prefer, as I'm sure she's able to understand words.
Once you put her down in her bed, the only time you should go back is about every 10-15 minutes to look in on her. Remind her to lay down to sleep, or perhaps lay her back down. Don't get her out of bed, to hug or hold her. It's very hard to do and may take a few nights of crying a couple hours at first, but will shorten over time. It may be up to a week for her to fully cooperate. Hang in there!!!
She will realize you will not get her up once she's put to bed and not waste her energy. If you get her up, you are encouraging her behavior by rewarding her with what she wants, which is to get up, and not go to bed at that time.
My questions to parents are, Who's in charge"? Is it the parents or the child. Who should be in charge? At this point it sounds like she is the one in charge when it comes to her bedtime. You as her parents know whats best for her & need to take charge for everyone's sake.
This is not the last time she will test her boundaries. She may test you again in the future once you have her back into a bedtime routine, or it maybe something totally different. If you give in, it will take longer to break the habit.
I hope she cooperates without much fuss!
Good luck to you!
K.