Appealing/Moving to reopen doesn't protect your status or give you a valid status to be here.
I would strongly advise leaving the country before 180 days pass from the expiration of your last L-1 back in November - some time in May, I'm assuming.
Technically, if the extension was denied, you were out of status from the expiration. As long as you don't stay 180 days past that date before leaving, the penalties aren't severe and you can still reenter on a new L-1 or other visa if one is obtained - either through the appeal/motion to reopen, or a new filing.
If you wait past the 180 days and then leave, you have a three-year bar to coming back here. If you wait a year, until November of this year, and then leave you have a ten year bar to coming back.
It's difficult to gauge the chances of success on the appeal/motion or on a new filing without knowing the reasons for denial. But, I would look into filing a new petition (without extension - you would need to get a new L-1 stamp abroad and reenter). This is normally much quicker than an Appeal/Motion - if they chose to review as a motion as the service center where the decision came from, you could have an answer in a month or two, but they normally don't. Once a case goes up on appeal, it can take a year or more for decision.
Have a lawyer evaluate the denial and whether there is a way to overcome it, and talk through a new filing vs. appeal/motion to reopen.
Since the extension request was denied you became illegal in the U.S. the day your I-94 expired. You are supposed to leave immediately. There is technically no grace period.
You began accruing unlawful presence in the U.S. the day your extension was denied. If you leave after accumulating 180 days of unlawful presence then you are barred from obtaining another visa for 3 years. Consult with an immigration attorney who can advise you about the specific option that may be available to you.