If you did not use varnish/sealer or Top Coat and you want to change your lime paint colour or maybe just freshen up your wall with a new layer, you can simply paint the new layer directly on top of the old one. Oftentimes, one layer is enough but sometimes two layers are needed to fully cover, especially if you want to change your colour. Just keep in mind that the wall always needs to be free off grease and oil stains.