Spokes can suffer from metal fatigue; when this happens, you can rebuild the wheel with all-new spokes (just did this last year for my tourer)—see Sheldon Brown's article on wheelbuilding. Replacing the rim is probably not required. I would wait and make sure it's necessary, though; two spokes in a year is annoying, but not unheard of.
For the tour, I'd go ahead with it. I would take along four or so extra spokes—this is usually a good idea anyways—the best way is to electrical-tape them to a seatstay—and also a fiberspoke in case you need a quick-and-dirty solution. If you do break a spoke on tour, it's not the end of the world. If it's on the non-drive side, pull over and thread a new spoke through. If it's on the drive side, evaluate whether the wheel is usable without the spoke (36 gives some redundancy); if not, fiberspoke it and take it to a shop.