[G&K] Faith & Espinage features are missing in old civ5 saved game

Hi all,

I've recently purchased and installed the God and Kings expansion pack and I notice a problem in my old civ5 saved game. I can't find Faith and Espinage features in my old civ5 saved game. But I can find them if I start a new game.

My question is how do you enable Faith and Espinage features in your old civ5 saved game without starting a new game? I really don't want to start a new game to have all the new G&K features since I spent so much time building the current empire.

Thank you.