The 31-year-old actress, who plays Chas Dingle on the ITV1 soap, first went under the knife for breast enhancement surgery eleven years ago.
Speaking to The People, Pargeter admitted: "I don't think I will ever be satisfied with my body. I'll always be able to find something else I don't like. I'm just not completely happy with the way I look.
"My boobs are being done again in August. I'm going a little bit bigger. They were done a long time ago now so I think, just as you change your tyres on a car, you kind of need to change your implants.
"My surgeon told me I don't really need my boobs to go bigger. After the first op I thought, 'Jeepers they're big', but then they go down. I'm a double D now so I'm going up a third again. I'll be the same but a bit fuller."
Pargeter joined the Yorkshire-based programme in 2002 and added that she has no plans to quit her role.
"I love my character because I get to go to work and do everything I sometimes want to do in my own life - I really get to mouth off," she explained. "I get a good reaction from the public because Chas has good intentions.
"I'm quite happy to stay on the show until the day they are unhappy with me or I get bored. But I am happy being based in Leeds, I feel settled."
Pargeter was nominated for sexiest female at the British Soap Awards this year, but lost out to Coronation Street's Michelle Keegan (Tina McIntyre) at the ceremony.