You should never give up on your inactive team members! Include them in your team email. If your team member was active but then dropped off, there may be a good reason. Don't judge or put pressure on them, but do let them know that you miss them and ask if they need help. You can send them an ecard or an email.
I agree that you should work with your workers but you never know when an inactive team member may turn into the best worker you have with the right encouragement.