Preheat oven to 375°F. Set aside a 9-inch deep dish pie pan.
In a large bowl, thoroughly whisk together jelly, arrowroot starch and lemon juice. Add grapes and mix well. Pour the grape mixture into the reserved pie pan.
In another large bowl, mix coconut oil, peanut butter, milk and vanilla extract until evenly incorporated. Add oats, flour, sugar and salt and mix until well combined. Crumble the topping evenly over the grapes.
Bake until the filling is bubbling and the top is golden, 35-40 minutes.