At least once a day during Passover, drink prune juice instead of grape juice.
Try some dried figs instead of matzah as snacks during Passover.
Eat lots of vegetables, soup, and salad.
Before Passover starts, make your own whole wheat matzah.
Join the Facebook group (I did): Passover = National Constipation Week for Jewish People.
(note: out of kindness, I will not attach a picture to this post).