Turn meat over. Add sweet potatoes and celery. Combine apple juice concentrate and jelly; pour over meat and vegetables. Cook, covered, on 50% power 25–30 minutes more or until meat is tender, spoon cooking liquid over meat and vegetables once. Add apple rings. Cook, covered, on 50% power 7–9 minutes more or until apple rings are tender. Remove meat and slice. Transfer meat, vegetables, and apple rings to a serving platter, reserving cooking liquid.