I am a very lazy brewer and I let my beer sit for a month a LOT. Like, most of the time. If/when you rack it to the bottling bucket, just carry over an ounce or two of the yeast cake from the bottom of the fermenter, and everything will turn out great. Now, if you'd have let your beer sit there for two or three months, well then you need to add fresh yeast. But one month? No problem at all, no worries whatsoever. The yeast is still alive down there and ready to eat your priming sugar, guaranteed.