Not being able to use soap is a myth, and re-seasoning a pan hardly ever needs to be done unless you're seeing bare metal.

After a hard scrubbing, put it on the stovetop, drizzle a small amount of oil in there, and high heat for a minute. Push the oil around with a paper towel. Your pan won't rust.

Use a metal scrubber and you probably don't need to use soap in the first place.