If your federal form 1040 shows direct deposit information on it near the signature line and that information is still correct, you don't need to do anything. The information would also be at the top of the filing instructions form. If there is no direct deposit information on your tax return, you will need to enter that information into an IRS online portal that will be opened soon. See this web site to track it's availability: https://www.irs.gov/newsroom/economic-impact-payments-what-you-need-to-know
It's possible my assumption at the top of this post may be incorrect. You should go ahead and enter your direct deposit information in the IRS portal when it becomes available.
