I just typed it?
Anyway copy your 'saves' folder that's within 'games' from the latstest build that you have.
Download the newest (0.43) build and paste your 'saves' in the 0.43 'games' folder and you're done.
Ah, yeah back when I tried to switch from 0.37 to 0.38 I looked up how to carry over savefiles, and I found couple of comments where you had to copy and paste it...
When I tried to do it without copy pasting it didn't work, so yeah I've been doing it like this just to be sure.. It's not complicated at all so I don't mind doing it everytime.