You really should make a new set of levels at some point
Maybe you can add water, which can be combined with milk to make More Milk, which can then be used to make jelly
Or maybe Soda. It would a be a bad substance that you need to get rid of. It turns milk and water into soda when coming into contact with those substances. It destroys Jelly, and you're not allowed to get rid of it by sending it off the stage. The reason being it's sticky so it'll get into and gum up the off screen machines in the factory. Your only option to get rid of it is feeding it to the girl
Or maybe you can add cotton candy or some other cloudlike substance. It'd be a gas, and act similar to jelly, but it would have reversed gravity, floating up instead of falling down
Or you can just make more normal levels which would also be cool