Currently The easiest way to check for node updates is to open the Palette Manager in the editor.
Thus, manual polling.
It would be useful and easy to realize a functionality, which would check for available update for installed nodes at startup time and e.g. every 4 hours (configurable?) after that. If some update is available, as a first improvement step some notification shall be given out in the header line. It would already help a lot. The next improvement could be (after a click on that header notification) to list the nodes with update available and select either some or all of them and let install the update for the selected ones.