The full-back was dropped after the 31-6 defeat in France and rested from this summer's tour to Australia.
It gave Lewsey the chance to recharge his batteries in the Himalayas and he returned to score 11 tries in total and two in the 29-10 final victory over Leicester.
Wasps thrashed Bristol and Newcastle in the pool stages, then beat Saracens 31-14 and Harlequins 26-19 before Lewsey, Danny Cipriani's two tries and a Chris Bishay score saw off the Tigers.
"I've had my first proper summer off for seven years and I've come back refreshed," said Lewsey.
"I specifically asked to play in this. I really enjoy playing sevens, getting my hands on the ball and you get the time and space to express yourself.
"The last few years have been frustrating both for my club and internationally. I just want to get back out there and enjoy playing.
"We played an awful lot of good rugby and I was delighted for the likes of Danny Cipriani and Chris Bishay."
England under-19 fly-half Cipriani has been billed as a potential long-term successor to Jonny Wilkinson and Charlie Hodgson - and Lewsey added to the rave reviews the 18-year-old has attracted.
"He's one of the most talented guys I've ever seen and he's got all the skills and talent to be a world class number 10," Lewsey said.
"Today was the first time he's really been on the big stage and now it's about how we manage him, because there's nothing he can't do on a rugby field."
Leicester's challenge was based around the try-scoring power of Tom Varndell and young lock forward Tom Croft, who finished with seven and five tries respectively as they beat Saracens and Worcester in their pool games before seeing off Newcastle 24-21 and London Irish 26-14.
Varndell and Matt Smith scored for Leicester in the final but ultimately they could not live with a Wasps side full of promising youngsters and expertly marshalled by Lewsey and England Sevens captain Simon Amor.