The Importance of Purification in Purgatory

The idea that you can't do anything in the next life will receive a promised reward has led some theologians to conclude that people must be totally passive in the afterlife. Paul is describing rewards for things that we do in this life. The Scripture says that we will reign with Christ in the afterlife, and reigning is an activity so we'll obviously be doing things. I don't see anything that would prevent souls in purgatory from being offered similar choices.