When you make a change in Sketch, you can update the assets is Principle by reimporting the artboards. It will retain everything, as long as you don't mess around with the naming of things.
Changes can also be deleting a layer, or adding a layer. Adding two layers into a group. Etc... All of these are trivial changes that are usually chaotic in prototyping tools.
When you make a change in Sketch, you can update the assets is Principle by reimporting the artboards. It will retain everything, as long as you don't mess around with the naming of things.