This is the next to last item on the Setup menu. This is a feature that you may or may not find useful. It takes the setup of the current league and starts a new league. The week number is set back to zero. Averages from the current league are carried over to the new league. Other stats and scores are set back to zero. You might want to use this feature if you keep playing with essentially the same group of people season after season. With this feature you won't have to enter all the information for the new league. You would just have to add new people, swap people between teams to make up the new teams, change team names, etc. Depending on the size of your league and the number of changes from season to season, this feature can be a real time saver. You will also have the option of cleaning up the sub list for the newly created league files.
When you select this menu item, you're asked if you really want to do this. If you say you do, then you must select a file name for the new league. When the copying process is done, you will still be working with the league you copied from. If you want to work with the new league, you will need to open the data files for the new league.
The program will also ask you if you want to clean up the list of substitutes by deleting them all for the new league, or just deleting any substitutes where the player name is Vacancy or Substitute. The substitute list cannot be changed in the normal use of the program to manage your league. Copying the league setup to a new league is the only way to delete substitutes from the league.