11g dataguard broken after primary ran out of space
Why would you re-initalize everything just because 1 datafile is missing?

On the primary database, create a backup of the datafile:

rman target /
backup datafile 71 format '/tmp/whatever.bkp';


Copy the backup to the standby, then use it:

rman target /
catalog start with '/tmp/whatever.bkp';
run
{
  set newname for datafile 71 to '/path/to/datafiles/whatever.dbf';
  restore datafile 71;
  switch datafile 71 to copy;
}


Then try again.