On python, you can repeat a value several times inside a string when formatting it:
>>> print "Hello, {name}, how are you, {name}?".format(name="George")
"Hello, George, how are you, George?"
But I don't know how to achieve this with elisp. I'm trying to make a function that returns the GPLv3 copyright text (This file is part of Foobar. Foobar is free software:) with the name of any projectile project on it.