Deputy principal Claire Williams said her team, which announced a strategic review that could see a sale, had met contractual obligations.
"I have confidence that we can replace the ROKiT money but we also have existing sponsors that we are very happy with and are being incredibly supportive," she told reporters.
"I think the world is going to be a very different place but I'm sure there will still be appetite to sponsor in our sport, a sport that is undergoing huge change for the good."
The season has yet to start due to the COVID-19 pandemic and will have fewer races than the record 22 originally envisaged. Williams will have a new livery when it gets going.
A $145 million budget cap has been approved for 2021, with further cost saving and technical measures to come to help level the playing field.
The former champions, last for the past two years, have lost a number of partners in recent years but Williams defended the team's record.
"We very much feel that we look after our partners in a fantastic way," she said.
"We're working with a new agency and redeveloping the way in which we take Williams to market. Williams has always done a good job attracting new partners into our sport and I believe we will continue to do so." (Reporting by Alan Baldwin, editing by Christian Radnedge)