The Womanizer singer and agent Jason - who split in August after five months together - were spotted kissing and cuddling at a California mall earlier this month.
A source told National Enquirer magazine: "They've been spending a lot of time together. Britney missed Jason so much when they were apart. They barely spoke. Now he's planning to join her on her Australian tour next month."
Britney's father Jamie who was made co-conservator of her personal and professional affairs following her breakdown last year - was instrumental in reuniting the love birds.
He found it hard seeing his 27-year-old daughter so heartbroken, and so asked Jason to consider giving the romance another try.
Another source added: "Jamie was really worried about Britney. She had all this free time on her hands during her tour break, and she was lonely. When Jason heard this, he came running. He really cares about Britney and doesn't want to see her hurt."
However, Jason still doesn't feel ready to settle down and has told Britney he wants to date other people.
A source said: "He let her know he doesn't want to be super-serious. Yes they're dating, but it's not exclusive. Britney's not happy about that, but she'll take what she can get."