Improbable. Once you have chosen an airline the terms do not permit changes until January of the next year. In practice, if no expenses have been reimbursed this year a customer service agent may make an exception, but once you have spent some of the allowance the probability of an exception is very low.
If anyone can confirm that they've done it, I'd love to know as well. It's very easy to get them to change if you've used none of the allowance.I'm stuck at $100 used of AA on my Aspire, and want to finish up the remaining $150 somehow.