i need friend advice?

well basically i have been friends with a girl for 3 years. this is the fourth year of our friendship. i have always thought of us as really close, even at one time called her one of my best friends. but lately it feels like we've seriously drifted apart. we never fought about anything, its just that she's friends with people i don't know, and the opposite. we are both seniors in high school, so i wonder if its the saying that "everybody changes senior year" which i have heard so often. idk, i just feel like we are not friends like we used to be. neither of us make an effort to talk to the other person or hang out. we just don't have anything in common anymore. do you think this is a friendship worth saving? what am i supposed to do in this situation?