Can everybody please download the new mandatory PLP app (1.27) from this thread and unzip it into your Steam\steamapps\common\assettocorsa folder, replacing any existing files.
What this does is read the number of track limit warnings from the server name, if present (e.g. you'll notice the practice server now has "P6" on the end of its name, to set the number of warnings to 6). If a "Pn" isn't present at the end of the server name, it defaults to whatever you've set in PLP.ini.
This allows me to set the number of warnings per season without you having to fiddle around editing files yourself.