I'm not sure what exactly you are trying to achieve, but there are several options:
1. You can remove the list item and create a new one, activating it using makeDraggable() again.
2. You can only change the properties of the existing data object (options.data - see https://api.daypilot.org/daypilot-scheduler-makedraggable/). In this case, you don't need to change anything else as the data source will be read when the dragging is started.