so, recently i got back into playing on the server, and i had none of the items I had before and the world actually seemed different.

my question is: does the world and player data occasionally get reset? 

The server got reset when update 50 came out.

so, then every update?

No, we try and not do resets often. We had to do one with u50 as our server had almost run out of storage.

Hopefully we won't have to do another for a long while