How about group winners in one tier, seconds in the next, etc. You can make adjustments for any odd numbers and turnover.
Edit: For example, if a team in tier 1 doesn't return, then the top scoring team in tier 2 (from the previous season's results) would move up tier 1. And so on... This would ensure that the most recently successful players are rewarded and playing each other. Others, like me, who has been in tier 1 but with poor results are placed in a more suitable tier.