Why did LaMia flight 2933 plan a flight longer than its listed fuel range?
The investigation is still on-going so I will stick to what is factually known. An airplane's range through the air should not be confused with travel over the ground, actual distance over the ground can vary significantly depending on the winds aloft. A significant tailwind will allow an airplane to travel farther than its listed maximum range, which is really just an estimate. We won't know what happened in this case until the investigation is complete. 

According to the information about the flight the pilot did not declare an emergency, so was told to orbit while another airplane which had a mechanical problem landed, this explains the loops.