Military fighter jets and commercial airliners are used for different reasons. One big difference between the two is the commercial airliners are aware how long it will take to fly from their take-off place to their destination and they can prepare for their flight. Military fighter jets are different because they may not know how long they will be in the air.
At this point, there are no ways to refuel commercial airlines while they are in flight. However, there is talk about being able to do this in the near future. This is especially geared toward those flights that are lengthy and cover very long distances. One example would be the trip from Australia to the United Kingdom because this flight takes a long time in air and must carry and store large amounts of fuel.