Why is the current earth replaced by a new heaven and new earth?

Les explains that after the great white throne and the lost are sent to the lake of fire (which is not hell), the Kingdom Age comes to an end. Revelation 21 then shows a new heaven and new earth. Les teaches this means the Kingdom will be interrupted and lifted off the planet long enough for a whole new planet to come on the scene. By the end of the thousand-year reign, this planet will have used up its usefulness. The new heaven and new earth will be a carbon copy of the Kingdom as seen in Revelation and the Old Testament, with the aspects of the Garden of Eden earth continuing on. That will be eternity, and believers will spend it not floating on a cloud but in a Kingdom on a new earth.