So, I put the Kim and Kat families (from the Lots and Houses Bin) into a neighborhood; and they are then removed from the Bin. I reset the neighborhood so I could play from the beginning, and would like to put both the Pets families into the neighborhood. My problem is that I do not know how to retrieve them. Is it similar to resetting the Neighborhoods?

Yes. You'll find them in:
C:\Program Files\EA GAMES\The Sims 2 Pets\TSData\Res\UserData\LotCatalog

Rename your existing LotCatalog to LotCatalog_BKP temporarily and copy the entire LotCatalog from above into your save game. Place the families that you want, then delete the new LotCatalog and rename your old one back.

Thanks.

Or alternatively, you can download Tarlia's cleaned-up versions here.

As far as I know, Tarlia doesn't have cleaned up versions of the Lot Bin sims. Instead, she has a special neighborhood with high EP requirements which contains all of the Lot Bin families, even the ones that the OP didn't mention wanting. These families are not in the original lots, but are in lots created by Tarlia.

Ok So I never got the Kim and Kat Families at all when I installed my game. I just downloaded Clean templates and I'm going to restart my game. Will they be there? If so where do I find them?

C:\Program Files\EA GAMES\The Sims 2 Pets\TSData\Res\UserData\LotCatalog
Ok So using Sims2Pack Clean Installer, I found them in the above location, now what? how do I get them in my game. I can't find their house or them!

They won't show up in the family bin because they come with their own lots, so you'll have to go into the catalogue with the premade lots and place them from there.

I have looked for them before in the lot bin, but I never found them. Now that I downloaded meetme2theriver's clean templates I'll check again. Thanks so much.

^ Look in the "occupied" lot bin. They're the only occupied ones that come with the game (there shouldn't be any other lots in that bin).