What I do is...
Let her finish, harvest, then cut it back very drastically. I leave 2-4 of the smaller shoots and thier leaves. Don't leave too much of the foliage, tho. Just enough for photosynthesis. Avoid contact with the severed ends of main colas and branches, and avoid spraying with anything till wounds heal. (couple of days should be fine) Have heard of candle wax being dripped on the severed ends to seal it off from microbes and bacteria, but have never found it necessary. This applies to pithy stems, and hollow ones.
I then flush again, and start her on the veg nute regimin.
Clonable shoots in a couple/few weeks.

Sometimes the soil will peter-out half way thru the re-grow, (water will not absorb, it just runs thru the pot) and a surfactant may be necessary. 1/2 to 1 tsp or so, of dishwashing liquid (not the antibacterial kind) per gallon of water works for this purpose. Just once should do the trick.

If you are short on space in your veg room, and are quite adventurous, you could give this a go:
http://boards.cannabis.com/grow-log/...ownsizing.html
Had seen it done elsewhere, and it worked fine for me, too.
(not recommended for beginners)