You can still purchase
travel insurance, but it will not cover pre-existing conditions. To have pre-existing conditions covered, you would have had to purchase the insurance within 7-10 days of when you booked your cruise.
Check the prices for travel insurance now, because I think the rates are lower, the closer you get to your travel dates. We booked a cruise 2 months out this past summer and the travel insurance was much less than what we would've paid if we bought it further out, and it was worth it to us to have the insurance, even though we'd be sailing within 2 months.
Don't forget, it covers medical situations while on your cruise as well as other cruise-related problems (lost luggage, etc). Personally, I think it's worth it, and we'll be buying travel insurance for our cruise next summer, but we'll wait and purchase it right before the 60 days out mark. (Prior to that we wouldn't need it because we could cancel without penalty at that point).
Hope this helps, good luck!
