I know you haven't explained why you want to do this, but, what's wrong with copy-and-paste?
The last time I looked, background-repeat does not allow one to specify a number of times to repeat an image. Basically, it's ON or OFF.
What would be gained if your wish could be granted? The HTML still has to be presented "x" number of times in the web page on the server to be displayed "x" number of times in a browser. At this stage in the evolution of HTML and CSS, that's how browser's work. Even using PHP or JS, they would add multiple copies of the chosen code to the page on the server so the browser could read and render them. If we believe that the user is an important part of a web site, there would be no difference in the speed of loading a page. Where/What would be the gain?
PS: Perhaps you would benefit from learning and using SASS?