I've never heard of the bar of soap. You probably didn't get rid of them all with your 6 cans. They probably still had some eggs and what not. I would call an exterminator. It might be a little expensive, but will save you a lot of aggravation and they usually have some sort of guarantee.

When I had my old house painted, the painters used caulk to seal the entrance to the huge hive in my house under my eaves. They said it looked like something on the Nature Channel, and they used about 8 tubes of caulk! (It was an old house, infested before I moved in.) Some of the bees ended up squeezing through my light fixtures in the dining room, two floors down. It was a bad scene. I agree - a professional exterminator is best.

I would use caulk or expanding foam to seal all holes or cracks which lead into the walls of your house. Search every square foot of the house exterior, it will be worth your time.

I think soap might work as it might not allow them to anchor their nest on the house.

Spraying that mint oil based spray where they might nest also seems to help. (Brand name Victor, used to kill wasps.)

Here's a link of the hive I had to remove.

Deena

Here is a link that might be useful: Bee Hive

For extreme cases like the above, which are inside your house, I would recommend an exterminator. But for nests which are external, you can do it yourself. Remember, yellow jackets have been known to eat through wood sheeting and drywall (gypsum board).