How long ago did you defoliate?
The reason I ask is that when I had the dodgy back-budding, I didn't pinch the tips at the same time as removing the leaves. Got poor back-budding and started reading up on defoliation, read about the tip removal part a couple of days later and went out to rectify my errors.
Once I did this it appeared to be too late and it just slowed the inevitable. Poor back-budding.
If it wasn't that long ago that you actually defoliated then it should be ok, but in my case it was..
So that particular potensai will have to wait till next year for a proper defoliation!
Have fun with it..