Spirit Airlines’ Flight Change Policy lets passengers modify their flights for a fee, which varies based on the ticket type and timing of the change. If changes are made within 24 hours of booking, no fee is charged. However, changes made closer to departure incur higher fees. Additionally, any fare difference may apply. Modifications are subject to availability and the conditions of the original booking.
https://www.toursntravelpro.com/flight-change-policy/spirit-airlines-flight-change-policy/