everybody who comes on here refers to times which is brag board stuff. you want to improve, sit down and honestly ponder how your season went this year. that should hint at your answers and better inform advice.
fast but weak endurance is one set of responses. decent endurance but can't run a lap very fast is another set. mental weakness or lack of competitive fire, another. get outkicked at the end, another. so, how do the races actually go? are you with the lead then fade? are you consistent splits but unable to keep up? do you feel lively but undertrained? do you feel tired and overworked? sit down and be honest with yourself. why do you lose to the dude who wins the races. you want to chase him explain to yourself why. then work on those whys.
example1: i grew up with our best miler around. i was faster than him in a sprint. i could stay with him for most of a mile. i had natural speed where i could, if undisciplined, lead XC races. if i want to go with him, i can hack the speed, i need endurance work, and maybe some mentality work where i fight feeling tired and cracking.
example2: i also played soccer up through college. i was a good defender and fairly productive attacker from the back. but i could get sloppy sometimes. fix: one college summer i get up every morning before work and do ball skill drills. i come back 3x as slick.
so sit down. what am i good at. where do my races go well. what am i weak at. where do i lose them. be honest. then work on what honesty teaches. that will help you 20x more than quoting times and asking for general training plans.