If you need to change your Spirit flight, you can follow these steps:

1. Visit the Spirit Airlines website and click on the "My Trips" tab located at the top of the homepage.
2. Enter your last name and confirmation code, then click on the "Continue" button.
3. Select the flight that you want to change, and then click on the "Modify Flight" button.
4. Choose your new flight dates and times, and then click on the "Continue" button.
5. Review your changes and select your preferred payment method to cover any applicable fees or fare differences.
6. Once your payment has been processed, you will receive a confirmation email with the details of your updated itinerary.

Alternatively, you can call Spirit Airlines customer service and speak to a representative who can help you change your flight over the phone. Must be aware that change fees and fare differences may apply, and that the specific options for changing your Spirit flight may vary depending on your fare type and other booking details.