The process of upgrading/downgrading the AP/LAP’s can be covered as with most networking in many ways. This method is one of my favourites and allows you to copy the code off of an existing LWAP node.
To copy off of an LWAP node:
archive upload-sw tftp:///c1130-rcvk9w8-mx.DEFAULT
Download IOS onto the device:
archive download-sw /force-reload /overwrite tftp:///c1130-rcvk9w8-mx.DEFAULT