One does not upgrade just because "it's couple of years old". If your laptop no longer works as you wanted it to - yes, it's time for upgrade. One of my laptops (used primary for Internet activities) is nine-year old Dell, and I see no reason to upgrade it "just because".
I have an "ancient" Asus Z96j -- it's still awesome. Buying a new laptop is an unnecessary expenditure. Few people know how to properly tune their OS, drivers, and game configs. If they did, then, they'd realize their laptop can still be used to run whatever it is the need.
A laptop should be purchased only if it's required by work, it's completely dead (e.g., the logic board is fried, and it may be simpler to simply buy a new laptop instead of replacing the defective part), or if you've exhausted all of your options when it comes to tuning. Turning to simple software solutions that do it for you is a place to start, but the majority of said "all-in-one optimizers" are junk. Learn your system and your OS and your laptop will continue to serve you faithfully. A quick purchase should be the last option, not the first.