Most likely there will be plenty of yeast left in the beer to carbonate the bottles. I would consider repitching if the ABV is high (~8%+) or if it spends more than a month in the secondary. If you do decide to pitch yeast at bottling, you can rehydrate a packet and put some of the liquified yeast in the bottling bucket - there's no need to add all of it since a whole packet is overkill.