Hi no problem :) no you don't need a new tester key to see updates, but it's going to be a while before the tester version gets updated.
I updated it fairly recently but that was just to fix some bugs (and test out doing automatic builds). I think it'll be a couple of months yet before there's another playtest release. If you want to make sure you have the latest update just either download the file again using the link OR if you're using the itch app you can select the game, click the settings cog, click manage and then check for updates there.