Let me clarify your question. First, you are saying that the "rules" of fashion mimick the laws of energy conservation. Second, you are saying that all fashion is cyclical and that nothing is ever lost because of the conservation of energy.
I disagree with the first part of your discussion because fashion is not naturally occurring. Fashion is driven in large part by the choices of purchasers at major stores across the globe. Those purchases are driven by what is offered by designers at a variety of Fashion Weeks throughout the year. None of this is driven by science or energy or anything other than the whims of a bunch of artists. Further, the idea that a fashion goes dormant is completely different from energy always being present.
I disagree with the second part of your argument because many parts of fashion have been lost through the ages. When is the last time you saw a woman walk down the street in a dress that is supported by a whale bone corset and features a skirt that is wider than any doorway you have ever seen in your entire life? This doesn't happen except in moves, and we call them Period Pieces.
Further, much of fashion is dictated by necessity, what is available, and one's station in life. War time fashions in the United States have varied dramatically. The "Little Black Dress" staple of women's wardrobes came from mourning tied to World War One and then the Spanish Flu worldwide epidemic. Everyone got so used to wearing black it became not a part of mourning but a normal thing to wear all the time.
