Frankly speaking, daily service may not be needed. Weekly service during peak season i.e. Oct-Jan and during tribal festival is needed. In fact ecor ran specials during mentioned time last year. But due to improper advertising, it didn't run with expected patronage.
Another problem is, only 5-10% of tourists use return train, which means a dedicated service between araku to vizag will return almost empty. Another reason why IR is not considering a new service is effect on freight service. This line is known for the profits it bring from freight service and would never compromise on that.