In general, you do not need to attend an US Visa in-person interview for renewal of your visa. You need to follow more or less the same steps as above, except there is no interview. The CGI federal system would indicate that you are eligible for interview waiver and let you submit documents for the same. If all goes well, you get your visa renewed with a new visa foil in your passport. Read How to apply for H1B Visa Dropbox to know the typical steps involved in interview waiver or dropbox.