Heat grill to medium heat.
Grease an 8 x 8-inch disposable foil pan.
In a large bowl, stir together cherries, ¼ cup granulated sugar, lemon juice and cornstarch until evenly coated. Pour mixture into foil pan.
Add oats, flour, brown sugar and remaining ¼ cup granulated sugar to another bowl. Stir together.
Pour vanilla extract and melted butter on top of oat mixture and stir to combine.
Sprinkle evenly over cherries. Cover and firmly seal with heavy duty aluminum foil.
Grill for 25-30 minutes or until bubbling around all the edges.
Remove foil and grill for an additional 5-10 minutes or until topping is set.
Remove crisp from grill and allow to cool for 5-10 minutes. Serve warm with ice cream.