Updates are triggered by something new showing up and as Dave3825 said when the DSD author(s) have time to do the coding work.
the process works something like this. Amajor system change or new feature needs to be implemented. This change then needs to be captured, described, Discussed (here in the threads) and submitted by the member ship. The coders then need to figure out what the change is in the data and how to decode the actual change packet. Next they need create code in DSD that isolates the new data packet reads it and processes it to a readable output. Finally they need to add that output to the display window so you can read it. In the background they also need to add the extra data field to one of the support files such as .group etc.
One newer feature that has started to pop up on many P25P2 systems is 'auto aliasing'. This is where the unit keys up and the system controller tells all the receiving units to display a radio name and not the RID number. EG RID 12345 transmits but the receiving units do not display 12345 they display "Pumper 1". A very nice feature. Some systems are lazy and all it shows is "Car 17" but you cannot have everything LOL. I am hoping the DSD people will get around to this in the future.
The best way to keep DSD alive and updated is to support DSD by registering your copy. Another way and this is MY personal suggestion not RR or DSDs is to make a one time donation like $5.00 to DSD even if you have already registered a copy. This shows the coders and developers that there is continuous interest in the program. This also makes it financially worth the developers personal time to invest the effort in adding in updates when discovered.