Riconsegnarmi is a reflexive verb meaning 'to redeliver myself' or 'to return myself'. It's a less common, more formal word than simply 'tornare' (to return), giving it a poetic and profound feel.
In the context of "La Vita Liquida," the singer uses it to express a desire to return to the sea, symbolizing a return to a fundamental state or origin, after experiencing the fluidity and impermanence of life. It evokes a sense of surrender and reconnection.
Brunori Sas builds this whole song on one word: liquido (liquid). He starts with his own body, which bends to every situation ("si piega ad ogni condizione" [bends to every condition]), and alcohol taking the shape of whatever glass it's poured into. Then he keeps going and the list gets uncomfortable: principles, morality, work, sex, ideologies, values, even his sense of duty are all liquid. Nothing holds a shape of its own. The drink is the "miscuglio che mi aiuta a non pensare" [mixture that helps me not think], and the tear is the one that "mi aiuta a non vedere" [helps me not see] what he has become: "un uomo liquido" [a liquid man].
The chorus turns that confession into something almost hopeful. Under the sun he could "evaporare" [evaporate] and become a cloud, "magari un temporale" [maybe a storm]. In the last part he follows the water cycle all the way down, through "rocce secolari" [centuries-old rocks] and "letti di fiumare" (dry riverbeds; a fiumara is a southern Italian torrent that only runs after rain) until he hands himself back "al mare" [to the sea]. The ending just repeats "al mare" again and again, like a man who has stopped fighting the current. It's a sharp joke about how flexible we've all become, and it ends up sounding like relief.