extending runtime?

HI
I'll race this weekend. On our track I use approx 250mah per lap and our final race will be 15min for first time. I can make max 24 laps in 15 minutes so I need a 6000mah lipo but I don't have it:( My biggest lipo is 5300mah . My gearing is 14/46 right now and the smallest pinion that I have is 12T. Could I be able to run 24laps if I use 12t pinion or it wouldn't make such difference?