I dont think He repeating his journey from the desert, well yes he is, but not exactly, I believe he is repeating his journey from Jericho Hill, I seem to remember (but correct me if im wrong) Roland always stated that his Quest and Obsession to reach the Dark Tower, started after Jericho Hill. So, I think that he started the quest from the desert, but his past was different, changed, due to the last loop in his quest changing him.