Yes, you can. The expiration date will be the same though. Just go to guest services either inside the park or outside the park. You will have to get another AP but they will probably use the same picture.
As long as you aren't concerned about blackout dates, you could just upgrade one Power Pass to the Preferred Annual Pass and still get free parking, discounts, etc.
When you purchase a Power Pass using the lotto discount you will pay mre to upgrade to the Preferred Annual Pass because all an upgrade is is using what you already paid for the original ticket and putting that towards the regular price of the ticket you are trying to purchase.
Example:
Can I use a 2 day /1 park ticket to upgrade to a AP?
I know the universalstudio web site does not sell those tickets and I bought the vouchers for my kids at Westgate (I think I paid $60 each) and still have the recipt. I converted the voucher at the guest relation in April.
It was a long story, but the short question is does anyone know whether I can upgrade the ticket to AP?
These are called "Star" or "Adventure" tickets. (Star are for Universal Studios only and Adventure are for IoA only.) I have heard that the only ticket they can be upgraded to (with a fee) is a Silver Star which is a two day/two park if none of the days have been used.
I will find out for sure today though.
edited to add: Read Airwolf's post. It has the correct info.
A Star or Adventure Ticket can only be Upgraded to Two Things the first is a Silver Star which is a 2 Day 2 Park 2rd Day Free ticket that must be used in 6 Days. The other ticket is an Annual Pass.