Something doesn't seem right here. Liverpool's runway is 2286m in length and even at maximum weight that should be plenty long enough. MTOW is around 75t vs an empty weight of 41t for an A319. (Or 213kg for each of the 159 passengers)
LPL-GVA is just over 1000km, a relatively short flight for an aircraft with a (fully loaded) range of 6,700km. (Yes, I know, holding and alternatives could add 30-50%)