Done this before aint that a beeeech! if it ever happens again and the branch hasnt boke clean off,, and the loss looks as tho its gonna be worth the effort then 1) remove the big shade leaves , [they will demand more moisture than the branch can supply] 2) wet some sphagnum moss used for orchids, or even coco or cotten wool ,with some rooting compound , put the branch back in place and wrap the moss around would so capliary action wil draw in moisture and hormone. Youll get some small roots but a large nodule will also form that can transport all the nutes and sugars to the buds.
I reckon if u do it properly and its not to long into flower you may only lose 20% or so of the potential yield
I'm in my first grow and I broke a branch, used a pencil and duct tape and NOW that branch has the biggest buds on it! Next time gonna break all of them!!! lol NOT!!!