Iceland international Arnason only made the move to Pittodrie last summer but he immediately established himself as a key player in the team and has helped the Dons enjoy a solid campaign.
Aberdeen's recent form has been particularly impressive, with a 12-match unbeaten run equalling a record that was last achieved 20 years ago.
However, it was announced in January that Arnason would not be staying with the club beyond the summer after turning down the offer of a new contract.
Rae still hopes that a deal can be agreed, though, having struck up an effective partnership with Arnason in midfield.
Former Cardiff man Rae believes manager Craig Brown has assembled a strong squad and should do everything in his power to retain the services of such a vital player.
Rae told the Daily Record: "I would love it if Kari could stay beyond the summer and everyone in the team feels the same way.
"We all want him to remain at Aberdeen. He has been such a great signing and is an important player for us.
"Hopefully, he will agree a new deal as we need to keep all of our best players at Aberdeen and Kari is an important part of the team.
"I enjoy playing alongside him in midfield."