While TeamSnap pushes out schedule changes within one hour, Google Calendar updates on a 12 hour cycle for subscribed calendars, so you will need to wait for the next update. This means that depending on where you fall in the cycle, Google can take up to 24 hours to push the update to your subscribed calendar.
If you would like to force a refresh immediately, you will need to unsubscribe from your Google Calendar and then subscribe again. When pasting the Full Calendar URL into the Other Calendar – Add by URL field, tag on the following to the end of the URL ( right after the .ics ) ?query=1
If you are not sure how to subscribe, you can review the steps in that help article.
For example, your URL with look like this: http://ical-cdn.teamsnap.com/team_schedule/yourspecificteam.ics?query=1
This will trick Google into thinking that you are requesting a totally new URL. The extra query parameter will be ignored, but Google will be forced to make a new request and won’t use their cached version. Make sure you unsubscribe from the existing calendar before trying this.