Theme updates are available from the ThemeFlood website. Click onto the support page and follow instructions from there. Theme updates are installed as new themes, so your old theme is not changed. Normally you can switch a project to a new theme simply by selecting the new theme for use in RapidWeaver. Take note of the change logs (list of changes) against each theme update. Normally it is not possible to transfer customsiations such as saved styles to a new theme. It is often quicker and easier to set them up fresh again.