The striker scored a hat-trick in Town's 3-1 win over Doncaster in Portugal on Tuesday as he continues his comeback from an injury sustained in March.
It kept the 26-year-old out of action for the last two months of the season, but he still ended the campaign as the club's top scorer.
"My time in the USA was really good," Vaughan told the club's official website.
"I had been before when I was at Everton and it worked well.
"This time around it gave me an opportunity to work on strengthening my knee.
"I was delighted to hit the ground running and get some goals under my belt, but the most important thing is that I got some minutes into my legs and got back involved in a game situation.
"I missed the majority of the second half of last season and it is important that I use this pre-season to get back strong and fit."