With my sons the way to get them to stay in their bed is after we read them some books then I saw goodnight and leave my husband in there. Our new routine is that he gets them to lay down, turns the lights out and he tells them a story (makes one up). Sometimes they request a story about certain things otherwise he tells them whatever comes to mind. We find it makes them to lay down & listen and calm down. It seems to work plus they get extra time with Dad.

Maybe she wants some extra attention and is acting up to make you give her some?? I would recommend no iPad before bed and maybe some special cuddles & a book then a story. Also when the baby comes he/she can come in and 'read books too' which is what we do with our baby. We hold him if he is asleep or lay him on the bed and they like including him in story time.

Good luck!