Cancellara abandoned the Tour de France last week ahead of the birth of his second child, while speculation as to the financial stability of his current team continues to grow amid allegations of non-payment by holding company Leopard SA and unhappiness within the roster.
The Swiss powerhouse led an exodus from Saxo Bank to Leopard-Trek at the end of the 2010 season, leaving Riis unashamedly hurt. Cancellara reportedly apologised to Riis last September.
"I always tell my riders not to burn their bridges when they leave," Riis told the Ritzau news agency. "And I think he did that last year, but the world is not so big that you don't meet again.
"I think the people who know me know that I am always open to a dialogue with people who have turned their back on me."
On Sunday, Swiss newspaper NZZ am Sonntag reported that Saxo Bank is one of two options for Cancellara should he leave RadioShack-Nissan - despite the fact that his contract does not expire until the end of 2013.
"We have become both wiser and older," said Riis to the Swiss newspaper.
"All teams will be interested in getting Fabian Cancellara. But for now he has a contract."
The report also speculated that Cancellara is entertaining offers from the Swiss-based IAM Cycling project, which recently announced that it was looking to create a ProContinental outfit. In April, IAM founder Michel Thiétaz said that the team would have an annual budget of 4.9 million Euros guaranteed for at least six years. Of the 20-man roster, half of the riders would be Swiss.