It isn't likely, but you would have to contact Adobe directly to see about working out some form of credit. The PS/LR package is already heavily discounted compared to other plans.
I realize, but I have spent over $700 on the perpetual license products. I would love to have this investment pro-rated and the balance applied to the annual subscription. That's how you migrate customers with grace.
Not to belittle your spending, but I and others have spent multiples more than that and we already understand as customers that we get what we pay for and not much else. No one is going to disagree that what you are looking for would be a nice perk, but no one in these user-to-user forums can do a thing to assist you in your pursuit. You need to talk to Adobe customer support directly.