[Shazam]

Just get new planks then, if you're convinced that the joists are fine.

You might have another problem though. If you decide to use PT wood, the formulation was changed a few years ago, and any metal on your existing deck that touches this new wood will get corroded from it in short order. So you need to check for that, as well as get new screws (don't use the old ones!), or use cedar, or use SPF (and paint/stain it until you're dead) instead.