Marle's line about "everyone's world" is not specific to New Game +, Vehek. Everytime I've ever taken Marle into that battle she says it, be it a new game, new game +, new game *, or what-have-you. It must be determined by something else...could be that she was always on Crono's left, or the second PC slot...I think...in my party whenever I went in there. Given that most dialogue is switched up given who is in which PC slot, that's the most likely variable.