[X] Use your ships to evacuate the court and as many troops as feasible to Dragonstone.
We're probably doomed at this point anyway but:
King's Landing is untenable. We don't have the supplies for a seige. Doubling down on the Shade-of-the-Evening doesn't seem promising to me.
So far, our biggest successes have been at sea rather than on land. We still have a fleet that can contest our enemies on the oceans. Relocating to Dragonstone naval base is probably our best bet. Or least the most sensible way to lose.