The product I use is water. No conditioners, no detanglers. Water. I started this thing about five weeks ago, and my geldings mane is like, all glowy and soft. His tail, has grown a lot already, and what was once brittle, feels pretty darn close to human hair.
The truth of the matter is, you're not going to get an cleaner, or more natural than water. (Unless of course, it's bad water. 0.0)
I think think cleaning it out with water, then some conditioner, will do it good.
You say you try not to brush her mane- A little tip, if you ever have to brush her mane or tail- do it when it's wet. The hair gets stretchy when it's wet, so there's much less risk of splitting and breaking the hair. It'll just stretch. :)