Google has been updating Google + and Google Maps. If you created a link to allow customers to review your business on Google in the past, you may want to check it as it’s most likely out-of-date. Here are the directions to create a Google Review link to post to your website or give to your customers: https://support.google.com/business/answer/7035772.
This direct link to Google’s, “Create a link for customers to write reviews” will also tell you how to read and reply to reviews (highly recommended) and create a short link.