Unfortunately, there is no ability to set or change lineups after the conclusion of your league's championship.
We don't allow users to be able to set a lineup or have scores tracked for any weeks past the final matchup.
As soon as your championship goes final, your league is considered completed. We don't have a way for you to continue having points tracked or anything like that.
Once championships are over, you'll have the ability to renew your league for the following season immediately, and we encourage you to do so.