Welcome to the Disney Parks Moms Panel, Courtney!
I'm so happy you had such an amazing time that you're already planning your return trip to Walt Disney World® Resort.
You can absolutely upgrade your tickets to Annual Passes, even if you are already home! However, to be able to do this, you must have days left on your tickets and you must purchase the upgrade within 14 days of first use - you will be credited toward the purchase of your Annual Pass based on the number of days left on your recent tickets. I do know there have been some instances of upgrades being allowed outside of these guidelines - it's definitely worth the call to the Existing Ticket Hotline at (407) 939-7523 to see if you're still eligible. Unfortunately, tickets with no days remaining cannot be upgraded.
I also see you're a Florida resident, Courtney, were your 4-day Park Hopper tickets the
4-Day Disney Select Ticket available for Florida residents? If so, this ticket is valid for six months after first use and is eligible for an Annual Pass upgrade that just needs to be completed before the ticket expires; again, as long as there are days left on the ticket.
I hope this is helpful, Courtney! Please let me know if you should have any additional questions as you prepare to plan your next magical visit. As an Annual Passholder myself, I am here to help.
Faith