Don't change it for nothing.
During the off-season (if any), just remove the head and cylinder. It's very easy, and doesn't require anything else than basic tools and 2 seals. Then, you can see and measure the piston, and mesure the rings (put the rings in the cylinder, and measure the gap where it's open). You rmanual should tell you what the specs are. If you're good, don't bother unless you enjoy lightening your wallet of roughly 100$ ...
Never assume "6months, it's good". I did, and almost lost my engine. My bike is ported CR250, and when I opened it during winter, the piston was damaged, cracked ... you name it, and it was far from old. I will check it every 6 months, if not more often, but considering your bike is stock, you should be safe nonetheless.