The 3 dots on the top right have a "refresh" option.

I do agree that there might be a better way.

I'm using an arch distro, so take my advice with a grain of salt...however I use this version (and manually add an entry to Lutris to launch this version).

https://github.com/kyechou/leagueoflegends

Once I switched over to this method, I've had very little trouble launching LoL.