Ohhhh hi anon, she’s there alright! But we can only catch a glimpse of her (this is the last panel from chapter 38 and volume 9 of the manga):
Coincidentally (hint), this scene comes right before Levi-heichou appears for the first time in the trailer kicking Pastor Nick:
Anyway, it’s totally understandable we don’t see much of Mikasa or Levi in the first season 2 trailer. For starters, the Captain will be out of commission for the entire Castle Utgardt / Clash of the Titans arc because of his injury.
Mikasa’s almost absence in the trailer has a different reason, though - all her appearances this arc involve really, really spoilerish scenes (rescuing everyone from the crumbled Castle Utgardt, attacking Reiner and Bertholdt when they expose their true identities, chasing after Eren when he’s kidnapped again, being saved by Jean, chapter 50…) so I’m not really surprised they couldn’t show them in the trailer. Rivamika’s time to shine will come in the second half of season 2, which should cover the entire Uprising arc, so hang in there!
However, there’s a very important scene involving Mikasa and Levi right at the beginning of season 2 that I’m very fond of, can you guess which one I’m talking about? You’ll see me posting about it soon… (;