Raise the taxes!

You have no choice! Those are just some serfs, what could they do to you after all? You are the lady of the land, it is their job to work for you and pay you for the chance to work your lands! A little extra tax can't hurt anybody...

But even as you raise the taxes, they can barely get half the original amount... Not to mention they had to give you every last seed of wheat to pay as much as possible to avoid execution of slavery...