Menu: Filter Name of the filter
Mac: Cmd + F
Win: Ctrl + F
This shortcut applies the last filter you used again; it does not reopen the dialog box of the filter you used last so that you can change the settings before applying again. As you might guess, a separate shortcut is available for that as well. Also note that this shortcut works only during the current Photoshop session ”once you quit the application, Photoshop won't recall the last filter you used when you relaunch.