I think EVN increased the offer timeline to hopefully pump up EVN to $2 so that PXG get to 18c, and they hope than a lot of pxg holders will sell, why else would they increase the offer by 1 mth?
also, I think this gives Zijin time to come back with another offer, maybe even 20c for pxg, we know Z have the money and they really pxg just as much.