Don't worry about your speed. You should always ride at the speed that is most comfortable for you. Even if you are level 1, you're going to be out there with level 2/3/4s, most likely, as they tend to mix the levels among the riding groups. Please don't think that because you are level 2 you need to be faster. I can understand that you perhaps *want* to be faster, but don't let it stop you from learning more.
Personally, I would do level 2 and if the on-track coaches think you need to repeat some aspect of level 1, they'll work with you on it. They'll also remind you of the level 1 take-aways to get you back in the game, usually. Don't feel like you'll be not-quite-ready or the like. Even people who do level 4 occasionally get told they need to work on Throttle Control (a level 1 topic). Ultimately, even though you might be doing level 2 drills, you'll still have a chance to practice good level 1 skills while out there.
But obviously it's completely your choice (and $$$!) and you should do what is most comfortable for you.