My laptop's battery life has reduced.

It is absolutely normal for laptop battery to have such problem. BUt, in order to at least slow down this process here are some tips you should do. You should always use the original charger. Always fully charge the battery, when it is discharged. You should stay away from flawed usage. You should avoid the falling off and short circuit of the battery, too heavy pressure on it etc.

i agree with that the others have said .. that's the usual wear and tear of the laptop's battery .. if you do want to prolong the battery of the laptop, if you're at home, remove the battery and use the AC instead .. just use the battery if you're going out ..

yeah.its normal that your battery life will decrease after 3 years because of repeated charging and using.use it for some more days and try to gather some money to buy a new one before the current battery gets completely worn out

Its really obviuos coz u use it lot , so u need to take off if u are in home , thats what i do when im in home using my laptop coz it reduce Or just buy another battery but if u dont have money just take off when u are in home or using in just one place.

It could be, but all rechargeable batteries will have reduced functionality as they age. Getting two good years out of a battery that gets used a lot is pretty standard. Ebay is a great source for replacement batteries, that is your best bet. As to why you can't use your choice of power plan, you'd need to give more details to get a solution.