From my personal experience (though others experiences may differ)...
Attempting to feed a non-feeding ball python every day is a bad idea. My advice would be to leave your snake alone for 10 whole days without holding it or messing with it in any way except to change the water, etc. This should help relieve any stress in your snake that may or may not be present, and may or may not be one cause of it's lack of appetite. After about 10 days, you should notice that your snake is good and hungry. My ball usually show me it's hungry by constantly sitting with its heads out of the hide laying in ambush. Then here's what I do (most will politely suggest alternative ideas)....I feed a perfectly sized live rat in the cage on the same aspen bedding I've always used. Usually opening the cage causes my bp to retreat its head several inches into the hide, so i hold the rat near the entrance in order to arouse a feeding interest and then let the rat go at the other end of the enclosure.
Nothing beats triggering a feeding response like a live rodent...but you have to be aware of the possible dangers and take certain precautions. If your snake hasn't attempted a strike within 10 minutes then it probably isn't going to eat, so take out the prey and just wait until next time. You must not leave your snake alone with a live prey item. I'm sure you are already well aware of what could happen if you do...if not, then someone here will enthusiastically explain. Feeding *long-term* in the enclosure sometimes is viewed as a bad idea, but we are just trying to get the ball rolling here right? And lastly feeding on aspen *long-term* will also eventually lead to some very minor problems, but nothing you should be too concerned about.
Good luck! Let me know how it works out!
Jeremy