Chabad.org — English translation + Rashi
Torah Temimah: “בחודש השני בארבעה עשר יום” fixes the date of Pesach Sheni as the fourteenth of Iyar.
English: “In the second month on the fourteenth day, between the evenings, they shall offer it.”
Date fixation — the second opportunity has its own precise calendar slot.
The corrective Pesach is not left to personal discretion; it has a fixed day in the second month.