i've found 30 seconds or a minute in the microwave will re-energize a dry brisket slice pretty nicely, somehow.
Digging around on other BBQ sites not always as friendly as this one, you find stories of competition teams having a brisket that finished 6 hours early, so they were forced to cool it all the way down and re-heat it for turn ins 6 hours later, only to discover a massively juicy result and pull a #1 brisket from it. Home brisket may get the same thing from simple reheating, at least as far as I can tell.