[ranskye]

are you talking hormone manipulation?, yes it works mostly.
i believe it also spoils the fish in some ways and that it may just reduce its breeding life span. i wouldnt worry about the number of eggs produced but the amount of time it will produce for. if shes a very special koi dont play with them and you wont have that on your mind.
i have spawned many fish with hormones (and i have not yet proved this to myself that the spawns will dry out one day) but that is the word around the traps, it could be many more reasons why a continually bred fish from hormones loses its fecundity..as with most things though we would simply change broodstock after a while. surely you could have some of the offspring spawn for you later anyhow.
that said, i think that from time to time the fish should produce viable eggs even after years.
i once read that certain such hormones can be used as a birth control system in certain countries- probably by overplaying with the egg developement. i dont know if it is reversible with time at all in humans. who knows about fish??

with koi it is easy enough to have them spawn totally naturally, so long as the egg is up to scratch, as determined by how well the fish is conditioned.
keep them apart, then introduce them to the new water, i think barometric pressure can be utilised (storms) to advantage. think about what makes a koi spawn and manipulate that instead. a natural flow of hormones that trigger a spawn will result.
what you could do is aneasthetise the fish and check that the egg quality is good beforehand, i am assuming once again that you plan to breed earlier than they would normally.
keep her happy, move her gently into conditions that would have her spawn naturally and she should go fine.