spilled liquid problem battery

Hello People. I own a macbook air mid 2011 edition. Few month ago I had an accident and spilled liquid on the keyboard. It stopped working so I went to official mac service store where they said that it is basically unrepairable but few weeks later I turned it on and it worked but just when the battery is not plugged in. So now it works only without battery. But 90% of the time when I turn it on it needs ages to get into OS X and then it works extremely slow. Now I just did an SMC and PRAM reset and it appears to work better..My question for you is: should I invest into buying a new battery and hope that everything will work again as it used to(is there any guarantee that it will) or should I rather consider selling it as a broken computer and buy a new used one?