Toniaus, you would want to remove the blade (wilah) from the hilt. This is generally fairly easy because most often the tang (pesi) is fitted into the hilt by wrapping material or hair around it to make it fit tight. Every now and then you may run across a keris where pitch has been used and has hardened. Then you might need to heat the blade to loosen it. Twist the hilt (gently
) back and forth while pulling on the blade and it should come loose. Once you see how the blade is attached it should be easy for you to re-attach it.
Yes, definitely dry the blade completely at the end of the process and oil it.