last year i had a nose piercing that was almost healed, until i switched from a stud to a ring (so i could chain my nose to my ear...). the switching process went much worse than i expected and the wound ended up being open again, one week before departure. i had the same fear, and brought the standard stuff to clean it with. but as you might expect, i was pretty distracted, busy, dusty, and subsequently exhausted for the whole week and i definitely slacked off on the cleaning.
surprisingly, my nose was okay, although sore. maybe it has something to do with the dryness or the heat? since it's only a week of your life, you can always get back on the healing wagon at home. but if you do end up with a fresh piercing, clean it when you remember to, have some good tea tree oil handy so you can dab some on. and hope for the best!
oh yeah, and addressing already healed piercings: i have ten others, and have never had an issue with them whatsoever. if they're healed, they're healed. noooo problemo.