I have a question???What should I do?

I have a best friend, we where good friends ...since we where in different clrooms she made friends of her cl, I tried to do make friends with a girl of my clroom(and I did) I started sitting with her at recess and lunch for 2 bimestres, then I told my bf I was sorry and now I am starting to sit with her again... but while I was gone with the other girl she made friends with a girl and now that I am sitting with her she ignores me... what should I do????