Hi - usually the new accounts will be flagged when running the report (if you are using a copy of an existing management pack report). In this case, I would recommend that you manually add the new accounts on the lookup tab (hidden), adjust the formulas / layout of the report to include the new accounts and then save the layout.

If you run one of the standard reports (i.e. not a copy report), then the new accounts will pull through.

Alternatively, we have developed reports which automatically add new accounts into the report. Let me know if you are interested in this and I will put you in contact with our report designer.