The server doesn't have proper support for that unfortunately, the server is intended to be run 24/7. The player profiles are stored permanently when running Invasion so player progress is preserved over server restarts.
Basically, it would be possible for the Invasion server scripts to be extended so that it would save the info to which stage the game got to, and when starting the script, make it query the saved data and initialize the gamemode state so that it at least continues from the last reached stage, even if the actual stage progression would be lost.
Alternatively the script could be extended with a chat command that completes the stages up to a wanted stage, this would allow you to manually skip some stages. Currently there is
/0_win in-game chat command (or
declare_winner 0 in server console) that admins can use that completes the current stage and prepares to advance to the next one.
Some info about the server console commands can be found with
help and also with e.g.
help start_server. I guess console commands are largely not used these days apart from
start_script and
status as there's a bit more power in the XML commands
http://runningwithrifles.gamepedia.com/ ... _interface that can be useful in some rare scenarios. XML commands in files can be executed in the console with
execute 1.xml style.