The festival would be about more than just music, she said.
Mud games were also planned, along with a spa where mud treatments and yoga sessions would be available.
Tickets were "very much in line with our expectations", Ms Lewis said.
"I think we've predicted it quite well."
Earlybird tickets would be on sale until September 10, but Ms Lewis said they would sell out before then.
Organisers were expecting a surge of new bookings following the new line-up announcement.
The Mudtopia festival is based on a South Korean event and will take place at Arawa Park Racecourse over the weekend of December 1-3.
The main feature of the festival will be the mud arena, which will have 350,000 litres of liquid mud made from local mud powder poured into it.
Inflatable obstacles and slides would be placed in the arena for mud games, and a mud run was being designed.
Rotorua moteliers have received few bookings so far for the weekend of Mudtopia, but one said bookings were often made closer to the time.
"In regard to events, people are often booking two or three weeks out," Shelley Hobson-Powell of Emerald Spa Motor Inn said.
"We could have seven walk-ins a day."
Occupancy across Rotorua Motels' Association motels was currently low for that weekend, she added.
"It appears there are a lot of rooms available," Ms Hobson-Powell said.
About 30 per cent of rooms have been booked at the association's motels so far, she said.
Ms Lewis said people from out of town attending the festival should book accommodation and plan their trips well in advance.
"It just helps everyone plan a little bit better.
"There's nothing else like Mudtopia in the Southern Hemisphere, it will be one of a kind."
Full line up:
•Shapeshifter
•Peking Duk
•Chores
•Anika Moa
•Hollie Smith
•Jason Kerrison
•Jupiter Project
•Hamish Crocker
•Illbaz
•Melodownz
•Aroha
