Let me start by saying thanks to @Prinzhorn for this amazing tool. It really is a nice piece and has been a huge asset. I've built custom solutions for this kind of thing before, but this really adds an element of ease to it.
It doesn't appear there is a supported method for dynamically updating data attributes with Skrollr right now though. But as noted in a comment above there is a request for it. However I managed to hack something together that is fairly inefficient. I only performed this action on resize so it was used as minimally as possible.
- I used JS to remove all attributes from the element. This seems terribly inneficeint, but any attempts I made to just have it remove the data attributes didn't work very well at all.
- I added the necessary attributes back on that were removed. Then changed my dynamic values and applied new data attributes.
- Finally, I made a refresh call to Skrollr and only applied it to the element that I had updated. This helped to ensure that only the necessary parts were being updated.