I know one of the worst things about axis and allies is when, during a close game, the axis lose a significant battle near one of there final victory cities, and the game is turned on them. The reason I hate this is because the rest of the game is just the axis player sitting around, playing a pointless game, now that the combined economic power of the allies is significantly greater than the axis. In essence, the game ends there.
I propose the option of a “draw” more or less. Anytime the axis player feels he has no chance of winning he can declare he is going on the “defensive.” At this point he can no longer attack territories, fulfill any national objectives, and have any chance of winning the game. He also only receives half of his regular income. He can however, still make it a tie. If the Europe axis can control Berlin, Warsaw, Rome and Paris for X amount of turns, the game ends with a draw. The Japanese player, must control Tokyo, Iwo Jima, Okinawa, and Shanghai for the same amount of turns.
That way, the axis player still has a reason to continue playing the game. I guess this is a house rule but I already wrote it here :-P