Is there any way I can still sign a player whose contract expires at the end of the season?

Yes

Make sure to sign him before the end of the season or you loose him.

Also if he is on a 1 yr deal you can't resign him. He will automatically go into free agency at the end of the season.

Thank You Beercloud. I took over my team in Week 11 and was looking at the contracts and since there is no Contract link with his name I guess this player is on a one year contract.