RINSE clean plastic containers and lids with boiling water; dry thoroughly.
DO not remake more than 8 cups of jam or jelly at one time. Spoon unset jam or jelly into large bowl; stir in pectin. Let stand 30 min., stirring every 5 min. Gradually add sugar, stirring after each addition until well blended. Stir additional 3 min. or until most of the sugar is dissolved and no longer grainy. (A few sugar crystals may remain.)
FILL all containers immediately to within 1/2 inch of tops. Wipe off top edges of containers; immediately cover with lids. Let stand at room temperature 24 hours. Jam is now ready to use. Store in refrigerator up to 3 weeks or freeze extra containers up to 1 year. If frozen, thaw in refrigerator before using.