If you're talking about Patreon updates, bringing old saves to new builds is not possible, because when I make changes to the database the new version can't read older saves. If you're talking about public builds, the save you started in May's build can be carried over to July's and September's builds.
The patreon build is a build that's in development so there will be changes to the database (character balancing, new enemies, items etc.) so older saves won't 100% work on newer builds. I always make a pre-played save in each build to make it easier for my supporters to check out the new content. I know it sucks, but that's how game development with this engine works.