Lapsing is not a disciplinary action. In fact, the Church Order (supplement to art. 67) says that a person under discipline may not have their membership lapsed.
A lapsed membership is a church membership that is no longer valid. A baptized or professing member who moves to a location where there are no Christian Reformed Churches in the area (or churches in ecclesiastical fellowship), can be declared a lapsed member 2 years after the date of their departure - unless the member in question asks the elders to hold their membership. This does not apply to members with temporary absences from their homes.
The same rules apply to a baptized or professing member who has not moved, but fails to attend and support the church that holds their membership.