This should work whether you are going up a pot size or not, i think. Search function is your friend.Upcanning (repotting) - Score the rootball - pop the ball out and using a razor blade or sharp knife insert it about ½" into the rootball at the top and slice thru the exposed roots from top to bottom concentrating on any root spinout at the bottom. Rotate the rootball and do this about 4 times. Bury the “trunk” as deep as you can even if it means pulling off some of the lower leafsets. This will induce root output all along the buried trunk.
Take a weed puller, the straight rod type with a "V" in the end. Take that and push down with the "V" so it cuts across the roots. Start close to the edge and make about 6 or 7 cuts. Wait a day or 2 and repeat, getting closer to the tap root but NOT in the very closest root mass directly under the stem. The severed root tips will regenerate 2 to 4 new tips, like when you top just better. I do this daily and wrote a thread on it not long ago.Can anybody give info on root pruning since my grow area is small,plz help would not like to lose this crop.thanx and happy growing