Recaída literally translates to "relapse," often used in a medical context for a return of an illness or addiction.
In this song, it's used metaphorically to describe a romantic relapse. The singer is worried about his ex trying to force a "recaída" in his feelings, meaning she's trying to make him fall back in love with her and ruin his current relationship. It's an interesting and relatable word choice for anyone who's experienced an ex trying to re-enter their life.
Vitor Fernandes brings us a song about that all-too-common scenario: someone who didn't notice you when you were available suddenly comes back around when you're doing great and have moved on with someone else. He sings about how this person was out "beijando um milhão de bocas" [kissing a million mouths] and having a great time, while he was