Executive Summary: Don't.
This past summer, I noticed a lonely bottle of Double Mountain's winter seasonal sitting unrefrigerated at a place where sometimes the stock doesn't rotate as quickly as you'd like. I bought it on a lark, partly to say I did, partly to complain about how seasonals are creeping earlier and earlier in the year (Deschutes actually released this year's Jubleale less than two months after I bought the Fa La La La La), and partly to set up this brilliant blog post about a vertical.
So Friday night at a neighborhood gathering, we did an informal vertical tasting of the 2013 Fa La La La La versus the 2014 Fa La La La La (I think the 2013 one is the fuzzier bottle in the picture).
First impressions of the 2013 Fa La La La La were good: oh yeah, that's the piney bruiser we were looking for. But then we tasted the fresh article from 2014, and there was simply no comparison -- the fresh bottle was approximately 100 times better than the old one. It had the same piney bitterness, but far more floral hop aroma and a much more pleasing flavor. Highly recommended this year.
Now, perhaps the old bottle would have held up better if it had been stored properly for the past year (it did spend 5 months in my refrigerator). But why risk it? Drink it fresh.
Hey, did Double Mountain stop re-filling their bottles? It was a noble idea, but I notice the deposit on them is only 5 cents these days, and the newer labels don't mention re-filling.