[xAndrewx]

  //Loading all the possible var names...
  vars = file.getVarNames(); 
  //However, you're only wanting to remove this
  vars.remove("mudid"); 
  //Shouldn't it be
  vars.remove(this.muditems[0].mudid);

Looking more into it

  //You're removing vars, then you're trying to assign a new var...
  vars.remove("mudid"); 
  vars.remove("mudtype"); 
  for (i = 0; i < vars.size(); i ++) { 
    this.(@ vars[i]) = file.(@ vars[i]); 
  }

Use this loop

  for (temp.currentVar: vars) {
    this.(@ temp.currentVar) = makevar(file.( @ temp.currentVar));
  }

If all else fails, make sure your way of setting the ''new vars'' actually works, try echoing the vars after you've added them. [Don't do the file. stuff, make it all one string being "hello"]

  for (temp.currentVar: vars) {
    this.(@ temp.currentVar) = randomstring("hello", "hi", "yo");
  }
  echo(this.getVarNames());