So don't remove the data then. You would need to take extra steps to remove the data, so just do not remove it. Just get() the String property of the edit box and write the contents to a file.
If the "without removing the original data" just happens to refer to the file, then see the 'a' or 'a+' "permission" fields at http://www.mathworks.com/help/matlab/ref/fopen.html#inputarg_permission
