What can i do to improve my chances of my 92 cherokee making long trips?

my 92 jeep cherokee leaks gas when more then half the tank is full. I've brought it to several mechanics, and apparently it needs some engine work. However its a strong car, the previous owner has been driving it for years without trouble and i as well have not had a single problem with it. I NEED to drive it 6 and a half hours to skowhegan maine. This isn't an option, what can i do to improve my chances of getting there without a break down? Should i take spread the trip out over a few days, or should i just drive and straight through as possible? This car has made it 1-2 hours away and back without problems. What can i do, i need to drive my car 6 hours.