Lapis only knows what maybe half of the words that Peridot is saying mean. Ride jokey? Attraction? But more importantly, not real? That doesn't make any sense, because the reflections are talking back, and now there's another peridot in the mirror. While Lapis might be hearing what they're saying, she's not actively listening.

Importantly, she's opted to ignore Peridot in favour of the other peridot, the one who is trapped in here too.

How many gems are trapped here? Lapis actively claws at the mirror for a few seconds. "I'll get you all out, Peridot help me!" She's already moving to smash another mirror in. Their gems have to be around here somewhere.