Should I Upgrade My Old PC or Go for a New One?

I've had my custom-built PC for about 9 years, and it's starting to show its age. I don't play games as often as I used to, but I recently downloaded a fun game called ARC Raiders, and my system is struggling with noticeable frame rate drops even on low settings. Here are my current specs: - CPU: Intel Core i5 7600 @ 3.50 GHz - RAM: 16.0GB Dual-Channel DDR4 @ 1066 MHz - Motherboard: ASRock B250 pro4 - Graphics: NVIDIA GeForce GTX 1070 with 4065 MB - Storage: 2x 465 GB Western Digital SSDs, about 420 GB free I'm trying to figure out if I should upgrade specific parts of my PC, and if so, which components would make the most impact. Alternatively, is it more sensible for me to buy a prebuilt PC at this point? I'm looking to spend around $500. Any advice would be greatly appreciated!