There was a discussion last week at Philosophers Anonymous about whether an applicant who applied for a job last year and didn't get an interview should respond to an identical ad in this year's JFP. Spiros says, "obviously no," but the ensuing discussion was more positive. Some people pointed out that search committees can change pretty dramatically from year to year. A few people pointed out that they had done this with success.
It seems to me that re-applying is the right thing. The point about search-committee makeup seems right to me. Not only will different people be on the search committee, but the files will be distributed to committee members differently, so there's every chance that the decision regarding the initial cut will be made by a different person than last year, even assuming some overlap.
For another thing, if your file has improved at all over the past year, you should definitely re-apply.
For another thing, you should re-apply even if it's all the same committee members and your file hasn't improved. The process is capricious. Many of the decisions about which files to consider further are made arbitrarily. The fact that you didn't get an interview doesn't mean you were undeserving. It might just mean that by the time they got to your file they had 20 names for the long list already, so there wasn't room for you.
And even if you weren't good enough then and you aren't any better now, it still makes as much sense to reapply as it did to apply in the first place. It costs you barely anything. And even if they thought you were completely inadequate when they saw your file the first time, and even if they literally laugh at you when they see it again, I still don't think it represents a reason not to apply. It's not like you'd know they were laughing. Nobody is going to tell you that they laughed. They'll just send you the same PFO they send you the year before (if they send them--not everybody does).
So I say, apply widely and often. Even if it's for the same job over and over.