:grouphug: I'm so sorry. I have two 6th graders (twins). One loves to talk and goof around throughout the day so he lags behind also and writes/spells poorly. You could try to find out what actually motivates him which is what I have resorted to each day. It may be bowling and skating with the homeschool group, playing outside, playing computer games, etc. I would find his motivation and use it.
Also, has he given you any inclination as to why he's doing this? Any input on the lessons?