I had this problem with my son. Both of my children still get in my bed from time to time. I talked to my peditrcian and she suggested this. Have your routine, bath, story and then give them a hug and kiss and tell them good night, it's sleepy time. If they cry after you have left the room, wait 5 minutes, go in and consule by a kiss, but no talking. Go out and wait 10 minutes before going back in, etc.(add 5 minutes every time) For the child who gets out, keep putting them back into bed, without engaging in conversation. No water, no extra stories, nothing, unless they have to use the potty. I just kept repeating, it's time to go to sleep. We will talk in the morning.Honestly, it took me 2 months of doing this before it worked, but he didn't regress. He is now 6, I had problems for 2 years, before I went through it because i would be so tired and just give up, but trust me it was worth it!