Constipating foods: cooked carrots, squash, potatoes, bananas, cheese, white grains (white bread, white rice etc), applesauce, milk, any food fortified with iron, iron supplements.
Foods that help with constipation: peas, pears, peaches, prunes, apricots, plums, raw grated carrots, raw grated skin on apples, yogurt (the bacteria helps the digestive tract), old fashioned oatmeal, whole grains.
She should be drinking no more then 16oz of cows milk or soy milk a day, and she should be drinking at least another 10 ounces of water every day.
Sometimes kids with food allergies have constipation as a symptom, so keep that in mind.