iCalendar feed not refreshing
By default, the iCalendar feeds are cached in your database, to avoid making too many requests to the website providing the feed and slowing down your website. You could set the cache interval to a lower value or turn it off completely from the plugin’s settings page.
Alternatively, you could manually clear the cache by going to your calendar’s iCal Import/Export page and clicking on the Refresh iCal Data button.
If you are using a caching plugin, you may notice events not updating in your front-end embedded calendar. To fix this, you will have to exclude the page your calendar is embedded on from caching.