how to revive my battery?

My laptop battery was bought from this website https://www.all-laptopbattery.com/asus-u35j.html for about half a year. A strange problem occured and my computer is not charging as usual and wouldnt charge up to 100% only 99%. In addition, when i plugged in the charger, the machine also can't be charged. I try to check my battery with the battery health check tool and the result is, my battery is weak. Laptop batteries are expensive to replace. What should i do to revive my battery instead of replacing with a new one?