The series, which is still early in its second season, set ratings records for the women-targeted network.
The network announced the pickup Friday during its presentation at the Television Critics Association press tour here.
Lifetime also announced plans to highlight its annual "Stop Breast Cancer for Life" campaign with original movie Living Proof, the true story of the UCLA physician and researcher who developed breast-cancer drug Herceptin.
The telefilm will star Harry Connick Jr. and is produced by Craig Zadan and Neil Meron, executive producers of Academy Award-winning film Chicago. That film's star, Renee Zellweger, will also serve as producer of the Lifetime film, which will be cablecast in October.
Between Lifetime and Lifetime Movie Network, 40 original movies are in production, including material from John Updike, Candace Bushnell and true-crime novelist Patricia Cornwell.
For more Lifetime programming news, click here.
For the latest news and video from the TCA press tour, click here.