Theos - MobileSubstrate: if/else using default values

Question

I'm writing a tweak to edit the statusbar clock strings. I'm struggling to find a way to call the native settings if the tweak is 'disabled'. I thought that calling %orig would work. But it only works after a respring, I want to avoid a respring if possible! here's the applicable code:

%hook SBStatusBarStateAggregator

-(void)_resetTimeItemFormatter {
  %orig;
  // Hook _timeItemDateFormatter iVar
  NSDateFormatter *newDateFormat = MSHookIvar<NSDateFormatter *>(self, "_timeItemDateFormatter");
  // set new clock format if ST is enabled
  if(STTime && STIsEnabled)
  {
    [newDateFormat setDateFormat:STTime];
  } else {
    // USE THE DEFAULT FORMAT
  }
}

%end

I'm aware that this is probably not the correct usage of case for %orig. So for my 'else' what shall I use? I don't know what the 'default' format is going to be!

Any help appreciated.

LM