Kylie Jenner has had lip fillers injected once again. (Picture: Instagram)

The 21-year-old reality star showed off a plumper pout on her Instagram Stories, just a few months after revealing she had decided to revert to a natural look and stopped having her mouth enhanced.

She shared a photo of herself in a white robe with visibly fuller lips and wrote: "Thanks [Pawnta Cosmetic Dermatology of Beverly Hills] for coming through late last night with a lip touch up!(sic)"

Kylie Jenner's fuller lips. (Picture: Instagram)

The 'Keeping Up With the Kardashians' star - who has eight-month-old daughter Stormi with boyfriend Travis Scott - revealed in July she had had the filler removed after a fan commented she looked more like "the old Kylie" on an Instagram post.

Kylie replied: "I got rid of all my filler (sic)"

The Lip Kit mogul first admitted in May 2015 she had been using fillers and explained last year she took the plunge after a guy thought she'd be a bad kisser because of the naturally thin shape of her lips.

She said: "I was 15 and I was insecure about my lips. I have really small lips. And it was like one of my first kisses and a guy was like, 'I didn't think you would be a good kisser because you have such small lips.' But I took that really hard.

"Just when a guy you like says that, I don't know, it just really affected me. I just didn't feel desirable or pretty. I really wanted bigger lips."

The 'Life of Kylie' star originally used make-up to enhance her pout but turned to filler when cosmetics were no longer "doing it" for her.

She said: "I would overline my lips with lip liner just to create the illusion of bigger lips. And then finally I was like this lip liner isn't doing it. [I] ended up getting my lips done."