死灰复燃

lit. reincarnated in sb else's body (idiom); fig. a discarded or discredited idea returns in another guise

lit. to return in a swirl of dust (idiom); fig. to regroup and come back even stronger

old illness recurs (idiom); a relapse; fig. to repeat an old error

to revert to old ways

(of a person) to return to the fray after a period of inactivity; to jump back into the thick of things; (of sth that was once popular) to be resurrected; to make a comeback

lit. the soul of a deceased has not yet dispersed (idiom); fig. the influence still lingers on