I have rescued blueberry shrubs that were damaged by road salt, by over-watering in the spring. What happens is the salt in the soil dissolves in the water, and makes it's way down into the subsoil, away from the plant. It takes a lot of water to do this, maybe 50 gallons per shrub. I think I put down 15 gallons, waited a few days, and repeated. Then I waited a few days, and repeated a third time. The shrubs did eventually recover.

The people at your local office of the Cornell Cooperative Extension Service would be much better prepared to answer that question then most of us here. There is a big difference between having sea water on your soil for several days and having some road salt tossed onto a planting bed.
I would suspect that the quickest way to "fix" the soil in your raised beds, however, would be to replace it, if you can find soil to do that.