Combine cranberries and sugar in a food processor. Process with short pulses until the cranberry are finely chopped. In a large saucepan, combine berry/sugar mixture with remaining cranberry juice and lemon juice. Bring to a boil over medium heat, stirring frequently. Reduce heat and simmer, partially covered and stirring frequently, until cranberry bits are tender, about 8 minutes. Remove from heat and stir in gelatin mixture until gelatin dissolves. Cool slightly and pour into an 8 or 9 cup mold. Cover and refrigerate until firm -- at least 8 hours. Can be made up to 2 days ahead of time.