I have a large bay tree (in the ground) which doesn't mind being cut back hard. Don't prune in the winter though. Use secateurs to cut off the shoots rather than cut through the leaves with shears. Give it a good feed in the spring. Nice pot - hope the tree looks bushier next year! Does it get lots of sun?
I have cut back a standard bay in a pot that was in dire straights ( not mine, I hasten to add). I cut back by at least a half as it was dead looking for quite a while, only a few leaves hanging on. It has come back really well.