On our five-night Navigator cruise in April, we had sailed 20 nights before beginning the cruise. Upon boarding I went to Reception and asked about being upgraded to Silver the next day. Reception told me such upgrades were handled by the cruise consultant and that he would call me after the lifeboat drill.

After the drill, the cruise consultant called as promised. He said that we would be upgraded to Silver and that, since we only needed one more day to reach Silver status, the upgrade would take place immediately instead of waiting a day.

So, the moral of the story is that you should ask nicely for an upgrade.