The Hard Out Here singer said she had found "a little pocket of time" to return to the music world but did not have any long-term plans for her own recording career.
Allen announced her intention to retire from the chart world in 2009, going on to work on a fashion business and then concentrating on family life until she bounced back late last year.
In an interview with Q magazine, she said she is unsure whether there will be anything further following an album she is working on.
She said: "When my kids start school I really want to be there. There was a little pocket of time I had to do this. One last hurrah and then I want to write musicals and songs for other people.
"I'm already halfway through a fourth album. Whether I can stretch to a fifth, I don't know."
Allen, who releases her third album Sheezus next week, admitted she does not like her chart-topping single Somewhere Only We Know, which was a hit in December. Her cover of the Keane song featured in the animated ads for the John Lewis Christmas campaign.
She told the magazine: "I really love the Keane version, I just don't like my version - I don't know what I think about that."
Despite her hopes of moving into writing musicals, she said her first attempt would not see the light of day. She has been working on a Bridget Jones production but said: "It's really good but it's not going to happen and I can't say why."