As long as the red filter material isn't separating anywhere, you can clean and reapply the filter oil from K&N. If you want to replace, I figured out the generic K&N number instead of buying from Seadoo, which they are around $120 each. Bought mine on Amazon for $48 each. Here is the information:
K&N Universal Clamp-On Air Intake Filter: High Performance, Premium, Washable, Replacement Air Filter: Flange Diameter: 3 In, Filter Height: 5 In, Flange Length: 0.625 In, Shape: Round, RU-2430