SAIGON, May 31 (Reuter and AP). GOVERNMENT and Buddhist leaders of South Viet Nam today made another bid together to end the civil strife wrecking their country - and it was as fruitless as the others. The Buddhists' spiritual leader at the same time appealed to faithful to cease laying down their lives in sacrifice - in the way a 17-year-old Buddhist girl did today, burning herself to death in a street in Hue. Her name was Nguyen Thi Van. In a desperate act of protest against South Viet Nam's military Government, she soaked herself in petrol and touched a match to her clothing. She died later in hospital. The Hue high school girl was the fifth Buddhist to take her life in this way in three days.