I have read that grape could potentially help with constipation as well.
Based on this article (http://www.natural-homeremedies-for-life.com/home-remedies-for-constipation.html), you can try soaking raisins (which are actually dried grapes) in hot water. After the water has cooled down, crush the raisins and strain the water. Offer the water for your girl to try.
Can also try prune juice. If the taste is too strong, start with the diluted version first or try mixing it with apple juice. Children may take more to juices even if they don't eat the fruit.
Read more