Changing Pot in Flowering

Im about 4 weeks into flowering and i was going to change my plants to a bigger pot to see if that helped with root problems . If i change the pot will this kill the plant ????

No, just try really really hard not to fuck with the roots, be quick with the transplant, and water with Vit B and a little sliver off an asprin.
If you fumble around and/or tear roots when pulling the plant out of their original pots, it will stress the plant and it can stunt your growth a little. But if you can do it quickly and cleanly, youll see no pain and all gain
Remember to push the sides of the old plant container in a little to losen the soil, then turn the plant upside down and gently lift the pot off the plant, rather than pulling the plant from the pot.

That late in flowering I wouldn't expect much more root growth.