Try magnesium and foods high in it, like bananas. And lots of fiber!
Magnesium! Also probiotics. I use naturally calm magnesium before bed. Start slowly and keep upping the dose until she becomes more regular. I think we are all lacking in magnesium
If she will drink juice, prune juice (2oz) mixed with orange juice should help her go more regularly without needing medication. TMI but I also suffer from this, but as an adult now laxatives don't help anymore.