K.Z.
Do you make sure that you are spending one on one time with your little girl? Pick a day of the week, or every two weeks that is your day with ONLY your daughter. Leave your son at home with Daddy. Take her to the movies, out to eat, shopping, etc. It will be the day that the two of you get to reconnect and it will also show her that you love her just as much as you do your son. Just because she is older and can do more things than your two year old does not mean that she doesn't want your attention and affection just as much. :) Hope this helps!
K.