It really depends on how long you'll be back for next year. Since you're going for 4 days this year I'll assume you'll be going back for 4 days next year as well, but the advice could be different if you're taking a longer or shorter trip.
Here are your options...
Buy a new 4 day ticket next year... cost: $239.63 (including tax). This is your most flexible option. You won't need to worry about figuring out exactly how many days you need for your next trip, and if something comes up and you don't make it back next year then you won't have to worry about an AP expiring. If you're not absolutely sure if you'll be back within a year or you don't know exactly how many days you'll need then this might be your best option.
Upgrade to an 8 day non expiration ticket... cost: $165.08. This is your cheapest option, but also the least flexible. Once you lock into an 8 day non expiration ticket you'll be stuck with those 8 days. If you use 4 days this trip and then decide that you really want 5 days next year it will be very expensive to purchase another one day ticket to get that 5th day. Likewise if you wind up only using 3 days next year, then you would have spent extra money to have that extra 4th day. It won't expire, so you can always save it, but because of how the ticket prices work it can be difficult to effectively use a single left over day. If you know you'll only be back once next year and you definitely know how many days you'll use, then this might be the best option.
Upgrade to an annual pass... cost: $271.58. This is the most expensive option, but if you know you'll be back within the year (and ideally even come back more than once) then this might be a good option for you. You also might be able to get an AP discount on your hotel rate to offset the higher cost of getting the AP. This can also help if you stay offsite because the AP includes free parking. That would save you $12 per day.
