Why do you think you should update your BIOS; do you think that it will solve a problem or give you some advantage? If not, it should not be necessary to change the BIOS.
You can get an idea of what changes and improvements have been made by reading the descriptions that usually accompany the BIOS versions on the BIOS download site for each motherboard/laptop.
Here is an example; note the descriptions on the right. You can also google for the motherboard/laptop and the BIOS version to obtain more information on what is any the difference.