In a large bowl, mix the cake mix, 2 cups of the oats, butter, applesauce, and vanilla. Add the remaining oats a little at a time until the mixture just starts to form big clumps. (Discard the rest.).
In a separate bowl, mix the preserves, water, and lemon juice. Press 1/2 the crust dough in the pan. Slather on the preserve mixture, keeping away from the very edges so the fruit doesn't burn. Sprinkle remaining crust mixture on top.
Bake for 18-20 minutes, until the top crust is lightly browned.