Start gradual build up to peak high mileage ove next few months, take it steady to ebuild body and mind afte blown it. Do a few early fall 10k/half marathons to keep up racing morale and then go all out for a marathon in November/december time when weather conditions will be perfect for this gruelling event.
Dont put yourself down with 2.40 in those conditions thats average/good.
Stay focused and train smart , keep motivation high and you will succeed next time- be patient .
Good luck