Summer cross country training?

hello. i've been training for my senior year in cross country and have a goal of 17:00. i previously ran around 18:40s but knew i could do better if i could of pushed my self more. i run at least 50 miles a week 7:30ish and run mile repeats after. i also do push ups sit ups planks leg lift etc. should i change my routine or add somethings to it? any help is greatly appreciated