Rangers boss Stuart McCall says he feels sorry for Gael Bigirimana, but admits he should never have been signed.
Chris Gunter will stay at Reading, after the club took up the option to extend his deal by another year.
Benteke has been one of the stars of a difficult season for Villa, scoring 19 Premier League goals in his debut campaign following his arrival from Genk last summer.
That goal return has led to transfer speculation linking the 22-year-old forward with a move away from Villa Park but Lambert has revealed that talks are underway about his future.
"We've been speaking for the last few weeks, so we'll see what happens," said the Villa boss, quoted in The Guardian.
"It's important we keep the nucleus of the lads who are here and add to it."
Villa's form has noticeably improved since February, leading Lambert to point out: "I think it's only been the top four and Liverpool who have beaten us (in that time).
"Some of the young lads have played over 30 Premier League games now, and that augurs well for the future.
"I've got no doubt they'll be a lot better, because they'll know what to expect. They don't look like novices anymore."