Winger Cook and midfielder Rowlands were both on target in Tuesday night's 2-2 draw at Brentford.
The veteran former QPR duo have been instrumental in helping Orient climb the League One table after joining in late August, but their short-term contracts are close to coming to an end.
However, Slade said: "I think we are getting quite close, so I'm hoping we can conclude those shortly."
Slade has not ruled out adding to his squad but admitted there will not be much movement in or out before next week's transfer deadline.
"We'll have to wait and see," he added. "You never know with the January window, things can happen right at the last minute."