A report compiled by Richard McLaren last year found that more than 1,000 Russian athletes had benefited from the use of state-sponsored doping between 2011 and 2015.
Russia's athletics chiefs have since vowed to improve the country's record when it comes to doping, but Niggli has questioned the speed of the process.
"It's not happening at the speed I would have liked to see but it is happening," he told BBC Sport. "We are working with them to see if things can be put into place and a credible system be reinstated in Russia in the coming months [ahead of the Winter Olympics].
"We will see where they are when we get closer to the Games. They still have a number of months to do the right thing. The ball is in their camp, they know what they have to do."
Russia have been banned from numerous international competitions while the doping reforms are carried out, but the International Olympics Committee opted against enforcing a total ban on athletes.