Our little boy was the same, they do grow out of it (eventually). Does she prefer to go to sleep upright? We found out at around 3 months that he had silent reflux, so it was too uncomfortable to lie flat to sleep. You could try tilting the head end of her bed up.
We would go for a walk in the sling before bed time. It made him nice a relaxed before feeding or rocking off to sleep.
Good luck!