Have you done a lot of reading about demodex? What you probably know by now already is that demodectic mange is an immune system problem. It frequently strikes puppies, whose immune systems are only just developing. But in an older dog is very much means that the animal's immune system is defective.
The big problem with mitaban, of course, is that it is extremely toxic (it was actually first developed as a pesticide, then used on animals - but due to being highly toxic was removed from the market for use on animals about 10 years ago - incredible how many vets still have a stock of that stuff). Put bluntly, with mitaban it's a case of seeing who succumbs first - the dog or the mites (and it isn't always the mites). But even if the dog doesn't display any drastic side effects, continual dipping further hammers the hell out of the poor beast's immune system - so you can end in the vicious cycle of the immune system not being strong enough to control the mites, mange develops, you throw on the pesticide to kill the mites, further reduce the dog's immune system... with the natural result that as soon as the mite population recovers (which it will, since they're a natural flora of EVERY dog's coat), the further-weakened immune system can't control them and you're back to battling mange.
Sooo - where that brings you is straight back to the immune system. The key to beating demodex is not in pesticides, but in boosting that immune system so that the dog can control the mites itself. And in turn, the key to boosting the immune system is in high quality diet (preferably raw, next best is homecooked - chuck that kibble in the bin, or if you must keep feeding it, feed the best quality you possibly can and supplement the diet with real, natural-form food); in ceasing all unneccessary hits to the immune system (no vaccinations, no elective surgeries, no tick/flea treatments (more pesticide), no deworming or anything else of that type unless it's seriously necessary. Where you live would have an influence on that - but if you're not flea infested and not a high heartworm risk area, don't hit the dog's immune system with those chemicals. All of this aimed at giving the dog's immune system a chance to recover to the point that it can do it's job.
There are a few individuals in this world that really do have such a defective immune system that they're not capable of recovery by themselves. But that is a very low percentage. For the vast majority, support to the immune system is what is required to get it to the point of functionality that it can control natural flora such as demodectic mites. Hopefully your girl will be in this category, but you've got to make some lifestyle changes to get there. I don't know your position on vaccinations and so forth - but in your position, I'd think seriously before ever having this dog vaccinated again or any chemical that's not absolutely required applied to her.
