Single player hardly levels you up. (@Fizzer probably should make them worth way more points.)
Anyway, for now join this game https://www.warlight.net/MultiPlayer?GameID=12436324
and I will surrender instently.(Or you can play any other MultiPlayer game, as loong as you win you get way more points then singelplayer)
Think the requirement is Lv4, which is really low. But as I already said, SP don't give significant amounts of points.