Get yourself a round 1/8 inch chainsaw file and a good ski-tuning file. Have a good pick on hand to use as a reference. Don't use an electric power grinder, as they can overheat the pick and ruin the temper.
File the pick end first, trying to restore the original bevel angle, while not making a half moon shape out of the tip. Make sure you don't make the tip angle too steep as it will be very fragile; if it isn't steep enough, your placements won't be as secure. File the flat hook on the bottom, stroking outward from you.
Repair damaged teeth using the chainsaw file. Use the flat side of the chainsaw file to return the original bevel of about 45 degrees, but not on the first tooth. Go slow, and use the reference pick, as filing off too much is worse than filing too little. The pick will need to be retired when you start filing past the first 3/8 inch tooth.