Even though being told that you only have thirteen days to save the world in a game implies that you're working against the clock, it seems like that won't necessarily be the case in Lightning Returns: Final Fantasy XIII.
Apparently, the game will allow Lightning to halt the march of time by using an ability called "Chronostasis". This power consumes Energy Points (EP), which are also used for healing spells and the combat ability "Lightspeed".
While Chronostasis stops the flow of time, its effects only seem to apply during active gameplay. It will be cancelled if Lightning visits an inn or gets on a train.
A release date of 11th February has been set for the game.