No. Kibana does not store things in its local file store. Instead, it uses Elasticsearch as its data store, so upgrading is as simple as backing up any configuration changes that you've made and re-installing any Kibana plugins (most plugins are not expected to work across minor releases, such as 4.3 to 4.4 or 4.5).
Conveniently, you can test this out by installing Kibana 4.5 manually (download the tar and extract it) without touching Kibana 4.3. As long as Kibana 4.3 is not running, then you can quickly confirm that you still have all of the dashboards by connecting to the same Elasticsearch cluster (you can confirm it even if Kibana 4.3 is running, but then you need to either install it on another machine, which is fine(!) or change its startup port from the default of 5601).