Regular batteries. Daily use for about 2 hours a day... I guess the fact that you have to even ask answers my question. Most other mice and keyboard these days lasts for months under heavy use...How often do you use the mouse and keyboard? What batteries are you using? Next time time give us more information in your initial post.
If you are using rechargeables, what mAh are they? You should be looking at AA with around 2400-2800mAh and AAA with 800-1100mAh.