The 'cartoon wardrobe' thing where a character in an animated thing only ever wears one outfit doesn't bother me. That's just their design. 'But what about laundry' just isn't a particularly interesting detail to care about.
But if you have a character with one of those Always Outfits, and then there's a timeskip and they show up again a bit older than before, you have to give them something new to wear. I'm willing to ignore laundry, but I've never met a 15-year-old who wants to wear the same thing she wore when she was 12. Laundry isn't an interesting detail. How the character has changed over the timeskip, and how that can be represented in their design, absolutely is.
Hell, it can't even be the same outfit, becuase there's simply no chance it would still fit. The only way to explain the continued use of the costume is if this character intentionally chose to buy a larger version of exactly the same thing they were already wearing every day three years ago to wear every day now. That's an incredibly specific character beat. And it's not one that makes sense for most of the characters who do this. You're already making new art! Just toss two hours of wage at a designer to give them a character-appropriate new fit as well! You can keep the theme colour!
