Read his racquet. If you have to disguise a dropshot, it makes it harder to hit over and over effectively. Most likely he is telegraphing his dropshot, as soon as you see it coming, run towards net.
Attack his backhand. hit deep to his backhand so he does not have time to lob, and follow the shot to net as his first choice will be a dropshot.
Play closer in, you are standing too far back and he is exploiting that. Sounds like there is no reason to stand this far back against this player.