You can try to update system in runtime through installer (I haven't checked this).
However, if you just have an upgrade WIM image and you want to apply it remotely, the things are slightly complicated. In this case somehow you have to bring your current Windows offline and update it completely. It's feasible even remotely, but you have to implement your own upgrade procedure. I've checked the essential parts of the steps below and they will work on any Windows (embedded or desktop).
The procedure is: