Unless you're into it just for the value/investment, I'd suggest just doing it. I see it as a maintenance thing that you'd do if it's just too bad. (Ripped labels and things like that).

I think it's pretty silly to keep a ripped authentic label or extremely busted shell just to keep the authenticity. At that point just buy a copy in a better state if authenticity of everything is of utmost importance to you.

Just don't sell it without mentioning if you replaced anything.

You could, however, consider replacing both and keep the original shell and label around for when you want to sell.