I hope I'm not asking a question for which I've missed an obvious answer, but what happens in terms of Refresh when someone upgrades to a power that replaces an existing power?
For example, at character creation, say I picked "Inhuman Speed" which costs 2 Refresh. After playing my character for a while, and getting some advancements, I want to upgrade that to "Supernatural Speed" which costs 4 Refresh. Supernatural Speed replaces Inhuman Speed.
Do I still pay a full additional 4 points? Or do I just pay an extra two points to make up for the difference? Are the 2 points I originally spent on "Inhuman" simply lost when I upgrade to "Supernatural"?