There is no API that gives you the device tokens for which your app registered to APNS.
Assuming that your app doesn't send the device token to your server every time it is launched, you'll have to release a new version that would send the device token to the server. Then you'll get the device token of every user who installs the updated version and launches the app. You won't recover the tokens of users who don't install the update, but there's nothing you can do about it.
I hope you have better backups next time.