There are two reasons why Shakespeare repeated Sans (which means none) in the monologue All the World's a Stage (or Seven Ages of Man) delivered in the play 'As you like it'.
The first is that Shakespeare uses a meter in his poetry. Particularly iambic pentameter. This means that every line contains ten syllables.
Sans(1) teeth(2), sans(3) eyes(4), sans(5) taste(5), sans(7) ev(8)-ry(9)-thing(10)
Note that the other lines may contain 11 syllables as the current method of how we pronounce them differs in the Elizabethan Era. (Most people confuse the Elizabethan English to the Old English, which is something to be corrected).
The second reason, is that Shakespeare wanted to add drama to the line. He used repetition, a common tool in literature, to convey emphasis on the message.