Bottle conditioning can increase the level of alcohol in your beer, however, it's typically not a significant change from the ABV developed by the primary fermentation. Priming sugar is used to facilitate the secondary fermentation.
Summary. Typically, the bottle conditioning lasts between two and four weeks, but it depends on many factors. Some beer styles require longer conditioning, which will prolong the process to several months in some cases. Be careful since both over-carbonation and under-carbonation can spoil your beer.