"To regain lost ground" means to recover or recapture something that has been lost or taken away, especially in a competitive situation. It suggests making progress or reclaiming a position that was previously lost or compromised. Full definition
The new screen size, 12 inches diagonally in a 3:2 aspect ratio, is another hint that Microsoft is much more interested in regaining lost ground in the laptop market than it is in trying to conquer the iPad. (theverge.com)
Speaking to GDI in November, Spark Networks said they were focusing on growing their flagship brand Elite Singles in the USA, as well as regaining lost ground in Christian and Jewish niches. (globaldatinginsights.com)
The Nikkei 225 tumbled as much as 7.1 percent on Tuesday before regaining some lost ground to close 4.7 percent lower. (baltimoresun.com)