Could've written this post til the past couple of months. What we've done for nearly 6 y.o. dd:
* Gone back to 100% pure products. We do this religiously for babies/tots but the older kids have been using our soap and mainstream "kid shampoos" because they used it at grandma's and thought it was so cool and yeah I know fabulous reason but there it is. We only use pure, organic, fragrance-free etc. products for soap, shampoo, and so on now.
* After a bath, a clear water "stand-up rinse" of her bottom.
* If she's not taking a bath that night, she does a rinse of her bottom before bed. I got a cheap plastic squirt bottle (the kind you get from CVS for use as a travel shampoo or conditioner bottle) and fill it with clean lukewarm water from the bathroom sink. She squirts it while sitting on the toilet which works perfectly because it rinses down, "the right way" and into the toilet. A blot dry with a towel, that's it.
* Help her wipe and remember to wipe front to back etc.
NEVER EVER EVER do bubble baths, "washing" of the area with any soap etc.