Carbon shafts are so durable that it's no problem to continue to use them over and over. Of course, I agree with what others have said, you should always check the shaft to ensure it's still flying true, and I would always use a different broadhead.

I shoot Carbon Express shafts, and have shot through several deer with one arrow, which is still in my quiver. This is one of the main reasons that I made the switch to carbon; aluminum shafts would nearly always bend on pass-throughs.