Does Nevada still have jurisdiction and do I need to ask permission again?

If no one resides in Nevada then Nevada no longer has jurisdiction. This response is intended to provide general information only and is not a substitute for speaking to an attorney.

Your ex must agree to your move to another state, or you must get a court order. If your court orders are still from Nevada (the case was not moved to Washington), then you must still file your motion in Nevada (as it doesn't make sense to move the case to Washington now, when you intend to move). Keep in mind that all you need under the law is written permission, but you should also consider what visitation schedule you will use with a greater distance between you.

Unless a matter is formally transferred to the jurisdiction of another court, the matters remains in the original jurisdiction.