"We need to show material progress over the next few months to establish to our senior lenders that a reorganization of the company is realistic and to avoid a shutdown and liquidation," Lampert said at the retailer's headquarters in Hoffman Estates, Illinois, according to exclusive audio obtained by CNBC.
The retailer filed for bankruptcy Monday, saddled by debt and declining sales. Under Chapter 11 protection, it is closing unprofitable stores and will try to sell roughly 400 of its better performing stores as it looks to stay alive.
Lampert's hedge fund, ESL Investments, is already in talks about potentially acquiring Sears, according to recently filed bankruptcy court documents. It is also in talks to contribute money to support the company through its bankruptcy, through what is known as a debtor-in-possession loan.
ESL Investments owns about 19 percent of Sears shares outstanding, according to the last data compiled by Factset. Lampert owns roughly 31 percent.
Lampert, who stepped down as CEO on Monday after five years in the role, said the speech marked the "second most difficult public speaking event" in his lifetime. The first was speaking at his father's funeral 41 years ago.