mufka,
Once during Chol HaMoed I ran out of white shirts that were fit to wear on Shabat or Yom Tov and called my rav to ask what I should do. He said that I absolutely must not launder the shirts, that it was permissible for me to buy some new shirts, but that I should seriously consider just wearing colored shirts on Shabat and Yom Tov because there was absolutely no reason not to!