The pumpkin makes up a huge part of this recipe, so I wouldn't recommend it if you can help it because I'm not sure how replacing that much of it would turn out. But if you don't have pumpkin and want to try these, I would recommend mashed banana first, then maybe a mixture of mashed banana and more applesauce. I haven't tried, but I would think using all applesauce would make these oat bars taste more like a cake, so I wouldn't recommend using just applesauce!