I think you can follow your older program structure, but I would suggest backwards planning. That is, look out to a target date/competition that you want to see results or participate in. Assuming you know your schedule ahead of time (i.e., the weeks that you'll be taken away because of work), then you can schedule around them. Given your exposure to weightlifting, I don't see you having an issue with taking a week off because of work and coming back to a solid workout. I would probably recommend repeating the week you left off at since you know your body was already exposed to it and, that way, you can continue progressing. These are just my thoughts. I, too, deal with that from time and to time and I found this works best for me.
Javier A. Sanjuan
Olympus Barbell Club
Dear God, please help me lift heavy and be awesome. Thanks. Amen.