The Shenzhen shuffle is the process in which a visitor to Hong Kong takes a short trip out of the country to somewhere close, for example Shenzhen or Macau, when their current visa is reaching its end date to refresh it. This allows their visa to be extended for another period of time, depending on their nationality, it could be up to 90 days to allow you to stay as a visitor. However this is a very risky way to extend your visa because at the border, it’s the immigration officer’s job to make sure you’re are a legitimate visitor, and if they believe you aren’t, they can deny you entry or give you a small amount of time, maybe a week, to sort your affairs and leave the country. The more times you use this process, the more likely you are to be denied entry. The amount of times you use this method shouldn’t exceed five times, however the immigration officer might question you even on your third or fourth time, therefore this is not a recommend technique to extend your visa.
If you decide for this option of updating your tourist visa, you must remember to obtain a China visa beforehand, as you do need to go out of Hong Kong before entering again, otherwise you won’t be able to update your visa.