Building up endurance - 9 year old kid

Hi, I've been following this forum for more then a year and this is my first post here. My daughter is 9 years old and she has been swimming for 2 years. For the last 8 months she's been training 4 days per week; half-hour dryland, one hour pool. She is a happy swimmer and they have great friendship within the team. Her free and breaststroke styles are quite fine. Her short-course(25m) 50meter times are: Free 40 ; Back 48 ; *** 51 ; Fly 50 But whenever she's in a meet, her stamina drops clearly at around 35m. As for the freestyle, her 25meter time is around 16 seconds. She usually turns before her friends, falls behind at last 15meter. It disappoints her. How can we help her to build up her endurance? What should we have her eat before the meet? Should we take her out for jogging, hiking, biking or any other physical activity? All suggestions and hints are appreciated. Thanks in advance!