The Roundcube team released a new version of Roundcube this week (0.8.3). Most of the changes include program bug fixes and language pack updates and there are no changes in the skin templates. This means that you can safely use your skins from 0.8.2 in your 0.8.3 Roundcube installation.
When upgrading, please keep in mind that the skin files are located not only in the "skins" directory, but also in some directories under "plugins". If you don't copy the skin template files to their corresponding plugin directories, some of your plugins might not work. To be safe, re-download the skins from our website and copy them to your new Roundcube installation.