Combine first 3 ingredients in a bowl; press mixture into a 13- x 9- x 2-inch baking dish. Bake at 400° for 10 minutes. Let cool completely.
Combine cream cheese and 1/2 cup sugar in a large bowl; beat at medium speed of an electric mixer until smooth. Fold in whipped topping. Spread cream cheese mixture over pretzel mixture. Cover and chill 1 hour or until firm.
Combine gelatin and boiling water in a medium bowl, stirring 2 minutes or until gelatin dissolves; stir in dates. Let cool to room temperature. Slowly pour carbonated beverage and lemon juice into gelatin mixture. Chill 30 minutes or until consistency of unbeaten egg white.
Fold apple into gelatin mixture. Spoon gelatin mixture over cheese mixture. Cover and chill until firm. To serve, cut into rectangles.