Ahoy Amanda,
My family have set sail on a
Pirates & Pals Fireworks Voyage twice over recent years and really enjoyed it both times!
I have just checked the Walt Disney World website and can confirm that at this moment in time, there are "No times available" for any dates in April 2017.
This is not to say that the event will not be taking place in April 2017, it simply means that the times/dates for April 2017 have not yet been loaded into the online reservation system yet.
My best advice to you in this instance would be to either call (407) 939-7529 to make your reservation over the telephone with a Cast Member or just to keep checking the Walt Disney World website to see if the times/dates have been added for April 2017.
I have not seen or heard anything to suggest that the Pirates & Pals Fireworks Voyage is being discontinued and am fairly certain that there has simply been a delay in releasing the times/dates on the Walt Disney World website online reservation system.
Wishing you a magical trip filled with memories which will last a lifetime!
Emma