1 Cup of Method dish detergent (any sent, though I am partial to the cucumber/melon. You can buy the large refill for around $5 which will make many, many batches of bubbles)
2 cups warm water
4 tablespoons of liquid glycerin (you can get this at the craft store or drugstore)
1 teaspoon of sugar
Mix all the ingredients together in a large container and you are ready to blow bubbles. I have found that the longer you let the solution sit the better it gets. This blend makes large, strong bubbles and worked great in refilling our bubble gun! If you try it let me know how it turns out, I am curious to hear if others have the same results.