Aw, this makes me sad. The new location is kind of annoying for me to get to now. It was the only Mexican food on the strip that I've genuinely enjoyed and felt that it was authentic.
I know this isn't Mexican (South American) - but there is an arepas place down near the Stratosphere that sounds amazing. I'm going next time for sure. If you're not aware, the best description I can give of arepas is that they are like an open-faced taco on a piece of flatbread and are also delicious. It's called Viva Las Arepas I think, I had the link open on Yelp but they never seem to copy properly onto TA threads.