"To update the roster" means to make changes or additions to the list of people or items that are part of a particular group or organization. Full definition
A newly updated roster of popular characters will make fans happy to dive into battles quickly, however the blunt absence of many fan favorites synonymous with the series can't be ignored. (thekoalition.com)
Not everyone is up for needing to update their roster sheets weekly. (sbnation.com)
NBA Jam Tournament Edition was an update to the original NBA Jam program, which featured updated rosters, new game play features and new easter egg items, which were combined with the same gameplay of the original. (retrogamenetwork.com)