Your filter should be fine providing you followed Katadyns cleansing routine after your trip. If you didn't then you will probably have risked bacteria build up and I would consider replacement, especially after the time period you describe. The routine you should have followed AFTER your last trip was complete was :
First remove the filter and rinse out the plastic housing. Then reinsert the filter cartridge and pump a litre of water through the filter to clear out any stale water. Then, fill a litre container with tap water and add two tablets of Micropur Purification or if not available two tablespoons of ordinary household bleach.
Place the prefilter into the solution (Thats your tube with the small plastic filter on the end) in the solution and pump the entire solution through the unit, until the litre container is empty then give it another 10 strokes to ensure that all the bleach/water solution has been pumped through. Then remove the cartridge and allow to dry. The filter will then be ready for your trip.
You could then rinse out the plastic housing again before putting it away.
Then when you use it each DURING a trip, simply remember to pump some water through it (Five to Ten strokes)before dispensing the drinking water into your container (To clear out any stale tasting water).
One last note, the hiker should filter upto 750 litres of water so if you were near that limit on your last trip and likely to exceed it during your next one, you should replace it regardless of any cleaning.
Lets face it, clean water is the single most important thing you need to keep you alive and the cost of a filter seems pretty low if your lying somewhere with stomache cramp or worse, because someone either didn't clean the filter properly or replace it when needed.
Hope your trip goes well.