Repeating Text Within a Word Document?
There are many different ways to accomplish this, but I think that the easiest is through Document Properties.

In your document, go to File -> Properties.  In your case, I'd probably create a new Custom Property.  Here, I've called it "Address", given it the type "text", and entered in the address of 23 Anytown Street, Anytown.  Click OK when you've completed this.


Back in your document, place the cursor where you'd like this text to appear.  Then go to Insert -> Field, select "Document Information" in the left list, then "DocProperty" in the right list, and finally enter (with quotes!) "Address" below, and click OK.  Repeat this anywhere that you want the address to appear.