To do a full update:
Locate and go to Documents\Klei\OxygenNotIncluded\mods\Steam
Locate folder 1934934314 This is the Mod ID.
Delete said folder.
Unsub, and resub to mod to start a fresh download.
This gives you a fully fresh mod install as if subbing for the first time. Useful for when steam don't properly update and keeps old files.

Note: To locate any mod ID it's in the pages URL. If viewing from the Steam Client, right click the window and select COPY PAGE URL, and then paste it into a browser.
For example: The URL for this page is
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1934934314

The id= at the end, is the mod ID.
This works for every mod, for every game on steam with mod support.

Instruction given by @SeaSharp