Rebuilding notebook battery pack...will it be better than original?

I have a low end Lenovo notebook that fits the need for which I purchased it. After only one year, however, the battery is showing signs of slowing down. Originally I got 2.5 hours as I use it, now closer to 1.5. If I rebuild the battery pack with high quality batteries am I likely to get some benefit - i.e. possible 2.75 hours or 3? or will I just be spending more money to get 2.5 hours?

careful w/ disconnecting the wires from the BMS. some of them shutdown permanently if they detect any unusual voltages from the sense lines so you may have to do a "live" transplant

and many notebooks use 4.3 or 4.35v cells so you have to be careful not to use 4.2v cells