The 'X Factor' judge, who split from Hamilton earlier this year, is said to be reuniting with him after reports emerged that he is willing to start a family, reported OK! magazine.
"Lewis has told Nicole that he wants them to give their relationship another go - and if they're still together in six months, he's agreed to try for a baby.
"She's not sure why and how Lewis changed his mind, but she's over the moon that they now both want the same thing," a source said.