I think it's different on each server. Max level of a server depends of how many players there is in the top level. If you have 14 teams in top level, 7 will be promoted, right... But I don't think they'll let those 7 to play vs. 7 bots next season, I rather think they put promotions on hold until at least 14 teams from 2 leagues are promoted... So I believe they move top level up every two seasons... I hope someone from any server's top level can confirm this.