You missed a TNT at The Strip last Saturday 12/14. I don't see anything coming up on the schedule. Best place to check is the Las Vegas Speedway facebook page.
Their next scheduled event is Jan 17-19 for Midnight Mayhem and TNT.
https://www.lvms.com/documents/2020-strip-schedule.pdf
They don't have many TNT or run what you brung events at The Strip. Very disappointing. I moved here from Dallas and there was something at 1 of the 3 tracks almost every weekend, weather permitting.