Yeah, I know what you mean, as I only get it on syndication, too.
Anyway, at the end of the last season finale, they crashed Thor's ship into the ocean to kill all the Replicators. Before they did that, though, they "beamed" up the Stargate and used it to take them to some other world right before Thor's ship went into the Earth's atmosphere and burned up upon entry and crashed into the ocean. However, at the end of the episode they showed one Replicator which had survived.
Then in the season premiere, it's a couple weeks later. They said right off the bat that Thor's people picked him up, though they left SG-1 on the planet they were stuck in. It toom them a while to get back because they had to wait til the SGC got the second Stargate out of storage (remember, in the finale they had beamed up the Stargate, which was now at the bottom of the ocean along with what was left of Thors ship). Soon after they get back, they find out that 1 Replicator survived and had gotten aboard a Russian nuclear sub. It then proceeded to create more Replicators and killed the Russian crew. However, since the new Replicators were made out of steel, they weren't nearly as powerful as the ones on Thors ship. So O'Neill and Teal'c got aboard the Russian sub, took out the Replicator Queen, and blew up the sub, destroying all the cheap Replicators. The End.
