Cross country help! Breaking 19 min?

I'm 15 a freshman on the xc team this is my 1styear of xc track or anything. my best time for the 5k was 21 min and now i beat it not to long ago for the past couple races i have been getting mid 20s i am so close to 19 min i know i can do it.their ar only 2 meets left cic and sectionals i want to be able to get 19 before the end of the season.I have always been a runner just haven't went into sports until now.i still have the rest of the year to do it but i want to get it in be 4 xc is over. becasue if i can get it down to 19 min then every year of my high school year i drope it a min i can beat to record it is 16 something min.do you have any tips