The "X Factor" judge helped create the girl group in 2002, which featured Sarah Harding, Cheryl Tweedy, Nadine Coyle, Nicola Roberts and Kimberley Walsh, reported Contactmusic.
"It needs to be the five of them. They'd do really, really well. If Bananarama could do it, why can't Girls Aloud do it?" he said.
The band played their final concert back in March 2013 after celebrating their 10th anniversary.
Louis, 65, said the group would do well because they had hits such as "Biology", "The promise" and "I'll stand by you" to their credit.