The 21-year-old, who operated on both the right and left for the Pilgrims in 2021-2022, was re-engaged for the upcoming campaign and has now officially put pen-to-paper.
The former Sheffield United and Tottenham Hotspur youngster made 36 appearances during his debut campaign at the Jakemans Community Stadium – scoring two goals in the process, including the winner at Brackley Town on Easter Monday.
"It's great news that Keenan is onboard for the new season," reflected manager Paul Cox. "He showed his versatility by moving across to the left when required and he ensures we currently have three really talented full-backs on the books.
"Keenan really developed during the course of the season and popped up with two crucial goals in the final few matches."