In a blender pour the tomatoes, tomato sauce, tomato paste, Italian seasoning, garlic, thyme, oregano, sugar, and lemon juice. Blend until the sauce is smooth.
Place the meatballs on the bottom of a crockpot and pour the sauce over the top of the meatballs.
Cook on HIGH for 4 hours or LOW for about 5-6 hours, until meatballs are heated through.