Auto-changing Memberships to the next level once an age restriction is hit

We base our memberships on age. Currently, there is no way to set a membership to auto-renew to the next level of membership once an age restriction is hit. This means that we manually have to go in and check and change memberships when this scenario happens, which is quite often. It's impossible to keep track of and we need to have it be automatic to be able to charge people effectively and not let people stay on a membership they are not supposed to be on. PLEASE ADD THIS!