I had exactly the same problem with Monty as a pup (he's a Lab too). Unfortunately I can't offer a solution. I tried everything I could find in books and on the net.
'Mouthing' is common for Labs and he eventually grew out of the worst of it. He's two now and still has a habit of grabbing people's wrists. Fortunately he does it quite gently.
Be patient, and continue to reinforce the fact that this behaviour is wrong. A simple 'No' will do the job. Eventually, your pup will either get the message that it's wrong (Monty never did
) or will grow out of it.
Good luck and enjoy your pup
