The vast majority of laptops these days are not CPU upgradeable. I am 98% certain those CPUs in particular are soldered onto the motherboard, the only way to upgrade would be to buy a different one with the CPU you want. A quick look on ebay provides only motherboards and laptops when you search for the CPUs themselves.
At that point you may as well just buy the i7 model flat out, especially if you can still return the one you have.
The vast majority of laptops these days are not CPU upgradeable. I am 98% certain those CPUs in particular are soldered onto the motherboard, the only way to upgrade would be to buy a different one with the CPU you want. A quick look on ebay provides only motherboards and laptops when you search for the CPUs themselves.
At that point you may as well just buy the i7 model flat out, especially if you can still return the one you have.