suddenly baby doesn't want to go to bed

Ashley
My 23 week baby is a good sleeper. She usually goes to bed around 8 pm but lately she just doesn't want to go to bed at night. We try rocking her and calming her with shh and songs but sometimes give in and feed her another bottle even though she just ate. What do you do when your baby doesn't want to go to sleep? I don't know why this is suddenly happening. She has a good routine and generally sticks to it and sleeps through the night. Any advice?