A.R.
As long as she isn't sick or in need of something critical, keep doing what you're doing. Just remain consistent and she'll get the picture. She sounds very persistent - a trait that will help her later on in life! I'm going to guess that you're a very fun and caring mother since she doesn't want to be without your company.
One thing you might want to try is to set a kitchen timer 30 or 60 minutes prior to her bedtime. Let her know "it is 30 minutes til bedtime, so let's make sure you get all your playing done before then". You'll help her to anticipate what's coming next. Once she has grown accustomed to this routine, you can help to empower her - let her begin to set the timer and make her feel like she is in control over when she goes to bed.
Good luck!