I don’t know if Disney's IT is up to the challenge. Past previews they checked at the attraction and verified your AP was used to enter the park.In the fine print, this is noted if you schedule a date when your pass is blocked out -
A preview registration for a date that is blocked out for your Pass type(s) will be automatically cancelled.
If you inadvertently booked a bkackout date call the AP phone line and see if you can pay to upgrade your pass. It worked for some guests GotG.
I'd be afraid your preview attraction might not get automatically canceled until you enter the park