I think you can renew them next season as well. A couple of seasons ago, I had a player I was willing to let leave, and he was still there without a contract on the first day of the new season, similar to a player you sign when you have no space in the squad.

Also, if he's a younger player whose market value and wage demands will skyrocket by the end of the season, it might be better that you sign the contract now if you're planning on keeping him for a while.