What can i do to make her love me?

okay so its like this i am a 16 year old boy just left school and doin my exams and theres this girl ive known since year 7 and have loved her ever since but the problem is i dont think she loves me back i came clean that i liked her in year 8 but she just said sorry matty i dnt feel the same way and it tore me to peices still does even 2day we are really good friends and like spendin time together but acording to her only as friends but i need to tell her that i just cant do it anymore becos of my uncontrolable feelings for her its the last exam and last time i go into school on wednesday and shes going to be there too so its my last shot what should i do should i stand by and accept that im never gunna get the girl i love and just back off or should i give it one last try???