The team announced last week that the Briton had left the Swiss-based team for personal reasons, with former Ferrari boss Binotto adding the role of principal to his other duties.
Wheatley has been linked to Aston Martin, the team run by his former Red Bull teammate Adrian Newey and now struggling with an uncompetitive Honda engine. He had joined Sauber, now Audi, in April last year.
"Looking at what his strengths were, the task he was performing - we need to fill the gap," Binotto told the website at the Japanese Grand Prix. "I can't simply add more and more responsibility and tasks for myself.
"My main focus is at the factory base where we need to transform the team, where we need to develop the car and the powertrain, so I will need someone to support the team here at the race weekend.
"We are considering it. We will organise ourselves and I am pretty sure that very soon we can announce it."
Binotto said Wheatley's departure, which came after media speculation about Aston Martin, had taken the team by surprise.
He added that the Briton had said he could not commit long term to the team for private reasons.
"We decided as Audi, given that he couldn't commit, to release him from duties. I don't think that as a team we have realised it yet. It was just (last week) and now we are here in Japan and we have a race weekend ahead."