Yeah. most likely you need to use the wizard again. My bet is that you didn't have that many levels when you created the menu, so that level of menu isn't defined in the .css.
You can normally add and edit menus by hand. The one time you can't is when adding a new menu to a level that didn't previously exist since it won't be accounted for yet in the .css. My guess is that there is no "level-2" in your css yet and it would be difficult to create by hand without the wizard.
You may be able to run the wizard on another page and add a level and use that css if you don't want to edit your menu directly.