I find that DS2 (age 2) will get out of his bed and knock on his bedroom door, then start calling out. It can happen several times during the bedtime routine. I avoid cuddling him to sleep, but will give him a little cuddle, tell him it is time for bed and put him down. I then make myself comfortable on a chair and just sit in his room. I will sing a song or two, then stay quiet, with only a sush or a "lie down and go to sleep". If he is awake when I leave the room, I will say night night and if he says it back, I won't hear a peep from him again. If he is being difficult I may have to stay until he falls asleep. If he is being a rat bag I will threaten to leave unless he behaves, usually I will need to leave his room for a short period and when I return he just puts his head on my shoulder and settles down for bed.