I followed the link given by Frank (thanks for the link), where Swamootra Neti is discussed.
I was interested to see that the speculated mechanism for the effectiveness of ones own urine is the same one that I speculated for amaroli -- namely, hormesis -- the triggering of a positive body response through the stimulus of a toxin. And indeed what more tailored a set of toxins than those your body is already getting rid of?
Swamootra Neti - Neti using one's own Urine
The idea of pouring urine through your nose would be, for nearly everybody,
a very strange and disgusting concept. Here we will not be dealing with the
subject in any detail, as this is a whole branch of yogic science, about which
there are more complete texts. The principle of Swamootra Neti functions in
the same way as that of Homoeopathy, where "the ingestion of like cures
like". The daily by-products of body metabolism such as urine, have within
them tiny amounts of tell tale substances which indicate the condition of the
body's internal health. The smell and taste of urine, when used in Swamootra
Neti, is a method of bio-feedback to the brain, which stimulates it to
gradually reprogramme the body's metabolism towards a better function with
lesser toxic waste products. This has a very potent healing effect on many
illnesses. When learning Swamootra Neti, there are certain dietary
guidelines which must be followed. To overcome any aversion to urine, one
is eased into acceptance of the practice, by beginning with weak solutions
and eventually moving towards full strength urine.