Ah the lost art of self rescue. As with all things you don't get good unless you practise, either voluntarily or when you are in the deep end..

This site has 3 methods for rescue:
kiteboardingtampabay.com/kiteboarding-self-rescue.htmlYour fallback should be this, stable and provides flotation, but no propulsion:
With enough practice under your belt, you will be able to go upwind in style and comfort