What kind of fatigue do you have? Is it common tiredness like your chops won't vibrate? Or is it some kind of swelling or pain?
One way of mitigating common fatigue is to choose a mouthpiece slightly shallower than your existing piece. A well rounded bite helpful too. Of course this might not be a good time to make a major mouthpiece change. However for Spring or next year you might consider some mouthpiece experimentation to get a little more bang for the buck.
My lips usually vibrate just fine, near the end my corners leak a little and the notes get about half a dynamic softer than when I started. It just becomes harder to play in tune. If I'm real tired I'll start feeling my face trying to do the work for me, at that point I usually just take a breath so it doesn't happen.