McKee's character Louise Summers was seemingly killed off by ex-fiancé Warren Fox (Jamie Lomas) in 2008.
However, she told Inside Soap: "I did get a call to return, but I had other commitments at the time, so I wasn't able to go back."
The 31-year-old, who has starred in BBC Three's Lip Service and HBO's acclaimed Game of Thrones since leaving the teen show, admitted that she is not ruling out a reappearance.
McKee added: "It would be fun to revisit Louise - she's a sneaky character, so she could still be around.
"We never actually saw her body, and I filmed a scene before I left with Louise still alive, so it could be used at any time."
The actress originally told Digital Spy of her plan to rejoin the serial three months after her character had 'died'.
McKee is guest starring in tonight's new episode of Lewis, airing at 8pm on ITV1.