Before you start shopping around for a new one, know that some laptops have soldered-in cpus. Some are even made non-replaceable. Now as for yours it is replaceable. Although there are limitations.
- Your chipset is HM76
- Your bios is only compatible with certain cpus
(Here is the link for your compatible CPUs)https://forums.lenovo.com/t5/image/serverpage/image-id/27303i8AB9EBBADF60739C/image-size/original?v=mpbl-1&px=-1
NOTE: This WILL void the warranty of your laptop and it is a lot more difficult to change a laptop CPU than a Tower CPU.
With this much restriction it would be better to instead build a tower pc on a budget or simply buy a newer laptop. Be careful with the components if you try to change the CPU as it will void the warranty.
How to change the CPU if you decide to do so.http://www.pcworld.com/article/148910/laptop_cpu.html#slide1