It sounds like you don’t need to be any more fit. If all your numbers are current, I don’t think you’ll have meaningfully large gains in any areas in 6 weeks.
What you shared is that your top competitor got away after the first lap. You might want to focus on strategy. Maybe be the one to attack early so this competitor cannot raise the pace and come around you. This will allow you to control the race early and hopefully bring it to a later point where their relative advantage is diminished.
Racing also is the best way to get race fitness. Jump in some minor races or find a way to actually simulate a race (maybe ride w a friend who is on your fitness level and tell them to attack you). Just riding hard on a trail solo won’t be the same - tho it’s better than nothing. Hitting a short track course would be what you want if short repeated efforts with low recovery is your weak spot.
Good luck