Also helping her exercise with her legs like she's riding a bicycle. We did that for our son it really helps.
My daughter will be 2M next week and would occasionally have a really hard time passing her poop. Now I put half an oz of white grape juice in her bottles twice a day (once in the a.m., once in the p.m.) and it's helps tremendously. You could also try prune juice in her bottles.
I wouldn't give her anything without approval from doctor first, a lot of old remedies aren't actually that safe. Do bicycle kicks and massage the tummy.
My baby often doesn't poop for days, the doctor told me that was normal for breastfed babies.