You forget the Senate. Mitch McConnell has a solid filibuster-proof group of Senators. If their president tells them this is right, they will support him.
And the resolution will not be repealed. It is a joint resolution and all of Congress would have to be involved.
Besides that, there is the constitutional question of whether congress can undeclare a military authorization. Once you start some things, you have to finish them.
"Guys, guys...Hey, you Islamofascists, Congress said we're finished, so you've gotta stop, too. Got that? Now, go on home. There's nothing to see here. Nothing else to do."
That filibuster-proof group of Senators will evaporate if Bush goes off half-cocked against Iran.
"There are roads which must not be followed,Besides that, there is the constitutional question of whether congress can undeclare a military authorization.
armies which must not be attacked,
towns which must not be besieged,
positions which must not be contested,
commands of the sovereign which must not be obeyed."
-- Sun Tzu, The Art of War, 7.3
Congress has the sole power to declare war, to levy an army and navy, and to regulate said entities. It's pretty clear they can.