OK, bad news first. There isn't much you can do to repair your laptop battery. There are companies that claim they can do what they call repacking or reconditioning but what you will find is the end result may not be worth the money spent on this service, not to mention that laptop manufacturers don’t recommend the practice.
In fact the manufacturers may void your laptop warranty (if it still has any) if you use a repacked or reconditioned battery. Replacing your battery with a new one is generally the best plan if you want to avoid any issues and extra expenses.
Laptop batteries are often not interchangeable with others due to things like power output and physical dimensions, most of the laptop batteries these days are moulded and are a custom fit to a specific model of machine. Take a look at the images below to see what I mean.
To sum it all up, best practice here if you need to repair your laptop battery because it's not charging is just to replace it with a brand new one and avoid any warranty or safety issues.