In a mixing bowl, combine gelatin and sugar; set aside. In a saucepan, bring cranberry juice to a boil. Remove from the heat and pour over gelatin mixture, stirring to dissolve. Stir in cranberry sauce and chill until slightly thickened. Meanwhile, in another mixing bowl, beat cream cheese, sugar, milk and vanilla until fluffy. Fold in the whipped topping and spread evenly into the pie shell. Beat cranberry topping until frothy; pour over filling. Chill overnight.