I say this, as Bushwacked will know, as a non-parent, but
– Putting her back to bed without saying anything to her
would seem to be the only option. Just keep doing it, for as long as it takes. She’s a lovely little girl, but let’s face it she’s stubborn and is at the age where she’s testing boudaries constantly. She needs to understand that bed (or more accurately sleep) time is just that, and what you say goes. No discussion.
I watched a similar thing on Supernanny (or something similar) once. The mother must have put the child back into bed about thirty times one night, there were tears (on both sides) and tantrums from the child, but she stuck at it and it worked.