sleeping girl

So I have started a bad habit of letting Christina sleep in my bed. At first it was when she woke up in the middle of the night and then when the boys would sleep over at my sisters or when she would fall asleep at 4 and sleep till 6. The problem is know when ever I tell her to go to bed she runs to my bed. I figure when I go to Korea Spencer can solve the problem or maybe I  will just have to start being strong (mean) and putting her in her bed.