Why did you not go with him two years ago? Anyway, at
http://www.cic.gc.ca/english/information/faq/work/work-faq08.asp you can see that you can have an open work permit if your husbands work permit is skill level 0, A or B and if he still has at least 6 months left on his permit. I am not sure which form to fill out for that but I am sure somebody here does??? He can also phone the call centre and ask.