...you should give them a break from time to time and launder them on the cold cycle several times in a row. Starch can cause your cuffs and collar to shrink, but several good, cold washes should alleviate the problem.
...and have you considered not starching them? Reasonable minds (e.g., my father and I) can disagree on this point. But think about it, say, in the context of a suit. Your pants and jacket? Soft wool with a luxurious fit. Your necktie? Silk, grenadine, madras, linen, you name it--a little bit limp. Contoured to your chest as it hangs. We are talking about soft lines and drape. Why stiffen your shirt?
On the other hand, if you wear your button-down shirts to work with jeans or simple chinos, maybe starch makes sense, since the shirt will be the focal point of your outfit.