A successful Russian Campaign would possibly have neutralized all Eastern threats for Napoleon: if the Russians had been defeated, the Austrians and Prussians wouldn't have moved an inch in my opinion and without them, the German minors would have stayed loyal to France. Napoleon could thus have focused his efforts on Spain afterwards: there is, of course, the problem that Napoleon didn't knew Guerrilla warfare, but I'm not sure if Guerilla would have been enough to vainquish l'Empereur. That would me by best bet among the suggestions.
The very last chance to survive past this one is not mentionned: the campaign of Napoleon was successful before Leipzig happened and he was even offered peace BEFORE that battle. Napoleon had been crippled by the Russian Campaign then, but he still had chances by that point. After his defeat at Leipzig, everything was over: the Allies would have stopped at nothing to get rid of Napoleon. Even the strings of victory he achieved in the Six Days Campaign/Campagne de France were not enough to stop the Allies from taking Paris. As for Waterloo, unless the Allies had went to war during the Saxony Crisis, I don't see how Napoleon would have stand a chance against a united Europe against him.