The Cottagers have been plagued by injuries this season and have only recorded one victory in 12 games.
Mahamadou Diarra, Mladen Petric and Damien Duff will boost Jol's options when they return to action in the coming weeks.
Bryan Ruiz produced a man-of-the-match performance in the 2-1 defeat to Swansea following his return from injury on Saturday, and Jol reckons fortunes will change for the team when the other players are fit.
"If players come back from injury, I think that will freshen up the squad as well," said Jol.
"If we can do something in the market, we will try to that. But it's not easy.
"You know as well as I do that clubs will wait and wait until you have to pay the maximum price and we will not do that."