to fall again, to fall back down, to fall back into (a habit), to relapse
Cette histoire ne va pas me retomber sur la gueule.
This whole thing isn't going to come back to bite me.
— Pixote, la loi du plus faible (1980)
Je suis en train de retomber amoureux de toi.
I'm falling in love with you all over again.
— Crazy Rich Asians (2018)
Elle a peur de retomber malade.
She is afraid of getting sick again.