Up grading members?

When you have different levels of membership and lets say a Free members time ends, how can I automatically direct that member towards the next level of membership once ended?

Also it would be necessary for that member to keep their details including user name, and login details, in other words directed for upgrade, through to paypal, then their account would show the next level of membership.

Greatful for any help!!! Jan.

By the way I’m trying to iron out any anomalies prior to launching the site. Thanks.