How do I get my ex-boyfriend to want me back?

ok...so im in 8th grade right now and last year in seventh grade, i asked out this guy that I REALLY liked and he said yes. i had known him for a long time. we went out for about 3 months, and i thought it was going pretty good then randomly he broke up with me. i was so sad for a long time and never went out with anyone else. i LOVE him. not im in 8th grade and we are in the same homeroom and in alot of the same cles. he acts like he likes me alot, but then he goes off and flirts with other girls. the valentines day is coming up and i would really like it if he asked me! i miss him a lot and i want him back..how can i get him back??