Stir sugar, cornstarch, and cinnamon in a small saucepan. Add apple juice and lemon juice. Cook and stir the mixture over medium heat until thickened and bubbly. Cook and stir for 2 minutes more. Remove the saucepan from the heat and stir in the margarine until melted.

Serve in a lidded pitcher.

Makes about 1 1/3 cups.