Nothing. There's no replacement for Rugby. I'm in the same situation and the best I can do is go on eBay.
If you want close alternatives, they are dime a dozen. Polo's shirts and pants are pretty similar to Rugby's except for the fit and the pony logo. J.Crew occasionally has preppy-looking sweaters and jackets. BB and J Press offer similar styles, but quality is all over the place.
to be fair quality was all over the place with Rugby too.
PRL is the best alternative, and there are some things that are pretty much Rugby pieces that were rebranded as PRL. I came across some seersucker tennis racquet critter shorts recently.
I got the J Press York St cricket sweater in a size small, for like 60-70 bucks, it fits nicely, especially over a polo.