You have to ask ASUS what processors are supported by THEIR BIOS. Then, you can select from those. However, your processor is soldered to the motherboard (or on a daughter card). If on the motherboard, you have no chance of upgrading (unless you replace the entire motherboard). I doubt the processor is on a daughter card.
Whatever the case, you likely have no upgrade path. Far a laptop this old, it is time for you to consider a laptop replacement.
Doc (not an Intel employee or contractor)