You would have to put the old link into the url attribute for each of the share buttons.
For example:
<a href="https://twitter.com/share" class="twitter-share-button" data-url="https://domain.com/old-link" data-via="your_screen_name" data-lang="en">Tweet</a>
Twitter also has an attribute called counturl
which might be worth looking at. You’ll have to do a bit of research on the others.