Colder temps will slow down growth on all but the best strains, and even some of those.

You put 1 tsp of molasses into 1 gallon of water, use this instead of plain water in your feeding rotation
Will it affect reveg? Honestly, I wouldn't trim a rootball of bagseed, just order seeds, they'll germinate faster than your reveg will, and you'll know the genetics.
The other option would be to take a few cuttlings now from lower branches that aren't budding much or have no buds, and try to get them to root by putting them under 24/0 and a humid dome for a few weeks, giving them a few minutes of air each day gradually adding more. Then switching them into a 18/6 schedule.

Revegging the rootball will take longer than trying to cross flowering clones back into veg. Its more than possible to do, and its a bit more advanced, but honestly, seems like you got a green thumb, I'd give it a shot (oh, make sure you follow the regular cloning guide...)