Britton here with the Shopify support team.
Aside from submitting your sitemap (which usually tends to be sufficient) you can use Google Webmasters Tools to directly ask Google to recrawl your site. Using the "Fetch as Google" tool explicitly asks Google to recrawl your site and can help in situations like this. You can find some instructions on how to do it here: https://support.google.com/webmasters/answer/6065812?hl=en.
I hope that helps you get your indexing with Google updated!
Thanks for the quick response!
I *think* I've tried that already and this is what Google is coming back with (doesn't seem good):
# Google adsbot ignores robots.txt unless specifically named!