Unmanned planetary rovers have traversed kilometers of Lunar and Martian terrain while performing valuable science. However, they still face mobility challenges including steep slopes and unstable soil that can entrap vehicles, as demonstrated by NASA's Spirit rover. Vehicles on Earth can depend on a human operator or rescue vehicle to tow them out of an entrapment, but remote rovers cannot, limiting their route to highly conservative path selections. To increase rover mobility on slopes and unstable soils, we present a resettable anchor launcher for independent self-rescue. The device launches a tethered land anchor away from the rover and then uses a winch to tow the rover up a hill or out of an entrapment. This paper presents the design of the launcher and its integration into a half-meter-long rover mobility platform with field testing at the NASA Glenn Research Center SLOPE Lab. We demonstrate repeatable launching and winching to help the rover climb a 17° slope of loose GRC-1 Lunar regolith simulant that it otherwise could not climb. Our work presents an alternative method to increase rover mobility, especially up slopes, and enables independent rover rescue, which could eventually increase mission duration and reduce risk of entrapment during extraterrestrial exploration.