Combine the crushed pretzels, sugar and melted butter in a bowl or large ziplock bag. Pour mixture into 9x13” pan and press to form a crust. Bake for 12 minutes, then let cool completely.
Meanwhile, beat the cream cheese, lemon juice and ½ cup sugar until smooth and fluffy. Fold in cool whip and spread mixture over cooled pretzel crust, making sure to go to the edges to seal.
Bring 2 cups water to a boil and stir in raspberry jello mix until dissolved. Remove from heat and stir in frozen raspberries. Pour mixture over the cream cheese layer and refrigerate until jello is set, about 2 to 4 hours.