General Visitor Visa - rejected

Dear Friends,

I need an urgent advice, Plz help.
i am trying to bring my wife's uncle to UK and it got rejected due to lack of documents.
I applied it online, but now when I re apply, should I apply it in the same use name account or should I make a new one and apply.
Should I give the details of previous rejection or should I ignore those questions when I re apply.

Can anyone plz do reply and help me.

kind regards

SC