The pilot of the Cessna 152 fueled the airplane to full tanks, prior to departure. He planned for his flight to take approximately 3 hours, and his past experience led him to estimate a 4-hour endurance for the airplane. After approximately 2.7 hours, the engine began to run rough, and the pilot diverted to a nearby airport. The engine continued to lose power, and the pilot decided to land in a field, when he realized he would not be able to make it to the airport. After landing, the pilot observed that the left fuel tank was empty. The right fuel tank contained fuel, and its fuel gauge indicated 1/4 tank full. The pilot then decided to add fuel to the airplane and take off from the field. During the attempted takeoff, the airplane struck a rut in the grass and nosed over, substantially damaging the wings and fuselage.