somewhere in Your qlikview environment there is an extract Application which create Your QVD files.
You need to add Fields or tables in there. If it build as an incrementall updated QVD then it have do be reloaded from scratch (beginning). Otherwise you only get the New Field on New rows all old rows will still not have for example Booking Reference data.
If its dimenssion tables you need then you need to add the tables in Your extract Application and create New QVD's, ex customer.qvd
When you have the New Fields in Your QVD then you have to add them also into Your Dashbord Application.