How to change storage for PersistentStateComponent

I used PersistentStateComponent like this:

@State(
      name = "Configurator",
      storages = {
            @Storage(id = "default", file = StoragePathMacros.PROJECT_FILE, scheme = StorageScheme.DEFAULT),
            @Storage(id = "dir",
                  file = StoragePathMacros.PROJECT_CONFIG_DIR + "/JHelper.xml",
                  scheme = StorageScheme.DIRECTORY_BASED)
      }
)
public class Configurator extends AbstractProjectComponent implements PersistentStateComponent<Configurator.State> {
    ...
}

Now I am getting warnings that PROJECT_FILE and PROJECT_CONFIG_DIR are now deprecated.

I'd like to rewrite it to the new scheme, so that 

1) everything is stored on per-project basis.

I read docs here: 

I think I just need

@Storage("filename")

if I need specific file or just leave storages in @State empty if I don't care.

Is that correct?

2) (this is the main question) after I change it, people don't lose settings in the plugin.

How do I do that?