For some pre-trip planning, go to the Chip Guide (chipguide.com) and use the "ChipGuide Query Facility" link in the left-hand column.
You can produce a list of $5 chips from OPEN casinos in Nevada. (It doesn't sort down to the city level, so you'll need to disregard all the non-Reno listings).

Compare that list with the chips already in your collection. You'll be able to get an idea of what's out there vs. what you already have in your collection.
The Chip Guide doesn't have every chip listed, but it's a start.

For further advance planning, Larry Hollibaugh (renocasinochips.com) also has an excellent listing of Northern Nevada chips. Casinos are sorted by City (i.e. Reno), but it doesn't distinguish between open and closed casinos. It's probably the most comprehensive listing of Reno chips around.