Children, and Colon Health

my 4yo daughter, Natalie is recovering from a severe bout of constipation, made worse by a large fecal impaction, and I was wondering if there is anything that can be done to prevent this from happening again. she's always had a slow colon, and usually only goes every other day. one of the problems was that she wasn't getting enough water, and also not enough fats or oils. I've changed that, but what else should I do?
this has caused me to become a firm believer in colon health, and I want to learn all I can. a book on the subject suggested a monthly enema, but isn't that a little excessive? also, she eats a lot of peaches, is that good or bad?

again, thanks for your help everyone