I’ve found the Refresh EPG call, I’ve created a python 3 script for it, but it should be trivial to convert to another language. Just get a plexToken and your DVRID
import requests
plexToken = ""
DVRID = "16"
plexURL = ""
refreshEPG = plexURL + "/livetv/dvrs/"+DVRID+"/reloadGuide?X-Plex-Token=" +plexToken
res = requests.post(refreshEPG)
if res.status_code == 200:
print(" Refreshing EPG")
else:
print(" Error Returned : "+str(res.status_code))