[User 224999]

@marcelveldt
Still getting access token errors after a certain amount of time passed with 1.1.7 version from your beta repo.
Running Kodi 17.3 on LE8 (the "Extended" version by escalade that has RetroArch and Chrome included)

Hadn't even been playing anything, just left the machine idling for a few hours (runs as a samba server) and came back to it and had the access token errors
Log:
https://pastebin.com/igLh5UE7

Also, is there some way to restart the spotify plugin or reauthorise the access token without needing to restart kodi?

The backgroundservice takes care of auto refreshing the token when needed.
This isn't done in the plugin entry as that will slow down the plugin and it will cause unneeded calls to the api.
Looking at your log I see a strange thing happening: Look around line 151
The service is stopped there and never started again so no token refreshes.

Maybe this was some leftover from the previous version.
Can you restart your machine and leave it running for a while ? It should print "Authentication token updated" around every hour.