Regresa means "returns" or "comes back." While it might seem like a common word, its repetition and central theme in this song make it incredibly impactful and memorable.
Lasso uses regresa to highlight the painful irony that everything in life eventually returns – the sun, the seasons, hunger, and sleep – except for the person he longs for. This poignant contrast makes the word resonate deeply throughout the lyrics.
"Todo Regresa" opens on one clear picture: "Tus labios rojos, tus lindos ojos" (your red lips, your pretty eyes), "Verte bailar en navidad" (seeing you dance at Christmas). Lasso is remembering one specific night with one specific person, and the whole song is what happens after that memory won't stop repeating. A year has gone by since it ended, "Hoy se cumple un año de que terminamos" (today marks a year since we broke up), and he's still stuck on a promise she used to make and never kept: "Siempre me decías regresas" (you always told me you'd come back).
The chorus turns that broken promise into a comparison with everything else in his life that does come back. "Al final, todo regresa" (in the end, everything returns), he sings, and means it literally: the sun, the seasons, even hunger and sleep all return on schedule. Then the line the whole song builds toward: "Todo regresa, menos tú" (everything returns, except you). He never raises his voice about it. He just keeps a tally of what comes back and lets one missing name do all the damage.