You could have dirt entering through the air filter. I rode one day at a dusty track and the next the bike would not run. The filter had been fresh but the dust overwhelmed the filter and then allowed dirt to go by.
Once all of your oil on the filter has dirt attached to it, the dirt has a direct route to go into your carb. Check to see if dirt is caked on your filter.
Every time you wash your bike, ie after every ride, you should check your filter condition.
Ted