In a saucepan, sprinkle unflavored gelatin over the cranberry juice; let stand for 2 minutes to soften. Add cranberry sauce and 1 cup of sugar; cook over low heat until sauce is melted and sugar is dissolved; about 10 minutes. Whisk until smooth.
Remove from heat and add cranberry gelatin (raspberry gelatin if you can't find the cranberry gelatin); stir until completely dissolved, about 3 minutes. Pour into 8 inch square dish that has been lightly coated with cooking spray. Cover and let stand at room temperature for 12 hours or overnight (do not refrigerate).
Cut into one inch squares; roll in remaining sugar. Place on baking sheets; let stand at room temperature for at least 3 hours. I let mine stand overnight to keep the gumdrops from weeping. Turn pieces over and let stand for an additional 3 - 6 hours. Roll in additional sugar if desired. Store in airtight container at room temperature.