Every time a we release a new version, we add, edit or remove strings in the plugin, and as a result, those strings are changed in the translation files. If you are using a translation file, you should update your translation files with EACH upgrade of the plugin.
All the strings can be translated and verified over at translate.wordpress.org. Any of the completed languages (90% translation or higher) should be translated there, and then the new values are immediately pushed out to everyone using that language.
If your language is not yet at 90%, you can add your translations there, then click the Export link at the bottom of the page. For example, take a look at export link at the bottom of the Stable version translation page. Once exported, you can upload the .po and .mo files in the business-directory-plugin/languages folder.