Scherzinger has been dating the Formula One driver on and off since 2008, and made the request before Hamilton resumes his busy racing schedule this coming weekend at the Belgian grand prix.
The former Pussycat Dolls singer changed her plans and flew into London from Los Angeles on Saturday, spending the day with Hamilton, then flying out late on Sunday in order to start work on the Judges' Houses section of the show.
"[Nicole] begged for some quality time with Lewis," an insider told The Sun. "It meant she had to step off an overnight plane and begin shooting straight away.
"She must have been exhausted but she felt it was worth it to spend just a few hours with her man. They're obviously very much loved up once more."
It was reported earlier in the month that Scherzinger will spend most of her rumoured £750,000 ($1.2 million) fee on chartering private jets, in order to see Hamilton as often as possible around the X Factor live shows and the closing races of the Formula One season.