There are Swiss consulates in San Francisco and NYC you can renew your passports through. When I was first moving to Switzerland, I had to get a visa from the San Francisco consulate. That was kind of a pain as I lived in Seattle at the time. Years later, after I had acquired Swiss citizenship, I learned that you can use the consulate in Vancouver BC as it is closer to Seattle. I'm going to guess that the OP doesn't have dual US-CH citizenship, but you can always travel back to Switzerland using the Swiss ID card and a US passport if you do have dual US-Swiss citizenship.