You don't want to change her food or dust bath...that can lead to more stress for her. Chins aren't real keen on their environments being changed a lot and it can take them a while to adjust. It sounds like you need to spend more time with her out of her cage and let her run over you and stuff like that. Maybe a smaller room for play where the two of you are in there together to make her interact more. A bathroom, (making sure the toilet lid is closed, of course) and that she can't get her foot stuck in any drains, would be a good choice. Put some toys in there with you and sit on the floor and let her run around...maybe offering a treat to get her to come closer to you. You don't want to overtreat her though...that could make her sick. You kind of have to keep up with connecting with your chin too and building friendship with her. I don't think it's too late by any means. It will take time though.