Jol lost several key players in the summer, including Clint Dempsey, Mousa Dembele and Danny Murphy, but he brought in Dimitar Berbatov among his recruits.
After a solid start to the campaign, Jol still wants to strengthen, with Norwegian defender Vegard Forren linked to the Cottagers.
He told the Fulham Chronicle: "It's a cliche but we always look for players who can strengthen our team.
"I want to build a top team and that needs a very good footballing side that can compete with the likes of Spurs, Arsenal and Everton."
Dempsey and Dembele departed for Spurs in the final few days of the last transfer window and Jol would like to avoid a race against time to strengthen in the forthcoming window.
"That would be fantastic because then you can strengthen your squad," he said.
"If you don't know what will happen three days before the end of the transfer window then you've got a problem like we had.
"But nothing is what it seems because after that we've been doing better than before."