Position an oven rack in the center of the oven and preheat to 325 degrees F. Coat a 9-inch springform pan with cooking spray. Wrap the bottom and sides of the pan with a large piece of foil and place the pan on a rimmed baking sheet. Put the pita chips into a food processor and pulse until fine. Add the butter and process until the crumbs are moistened. Press the crumbs into the bottom and about 1/2 inch up the sides of the prepared pan. Bake until the crust is slightly dry in appearance and fragrant, about 5 minutes. Cool completely.
Meanwhile, combine the yogurt, cream cheese, eggs, sugar, flour, vanilla, lemon zest and 1/2 teaspoon salt in a food processor and process until well blended and smooth. Pour over the prepared crust and bake until the center is just set, 40 to 50 minutes. Let cool completely on a wire rack, then cover and chill in the refrigerator for at least 3 hours or overnight.
Meanwhile, put the blueberries and pineapple juice in a medium saucepan and bring to a boil. Reduce heat to low and cook for 5 minutes, then remove from heat. Sprinkle the gelatin over 1 tablespoon water in a small bowl and let stand 5 minutes. Stir the dissolved gelatin into the hot blueberry mixture until combined. Transfer the mixture to a medium bowl, cover and chill until thickened, about 3 hours.
After chilling the cheesecake, remove the springform ring. Slice and serve, topped with the blueberry sauce. If the sauce is too thick, rewarm it in the microwave for 20 seconds at a time before spooning over the cheesecake.
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