Civilization – ny way to change victory conditions with the game already started

I made this online version of the civilopedia.

I think the best way is to manually allocate citizens in your city to work for things that generate more gold / production / food / culture over science.

For example, if you leave your citizen allocation for the "governor" (the AI), it will surely prefer a "2 production / 5 science" hex to a "2 production / 1 gold" hex, even though the latter is better for you. Remember that for manual allocation you must first open the citizen allocation menu in the city screen, and also remember you can allocate citizens in buildings, for the buildings that allow it (called specialists).

You can also leave the allocation to the AI and only direct his effort by choosing something to focus on, via the radio buttons in the manual allocation menu. Those work better when you want something specific, though, not when you want to avoid something specific.

Finally, remember that even after you have researched everything, you can continually research the repeatable "future tech" technology for extra points. It gets harder and harder to complete it every time you repeat it, so you can never have too much science if you go this route.

By the way, if you have built any academies you can now override the hex containing them with some other improvement / great person structure, that can also help if you want to redirect your efforts elsewhere.

EDIT the newest version of civ5 allows you to sell buildings - which is perfect for this case! Just sell all your research labs, universities, libraries etc. - sell all buildings that only give you science. Since you can sell only one building per city per turn, I recommend you start by selling the buildings with the highest maintenance cost.