Let me start by noting that this is the same basic process as adding piping to a project.
1. First, lift up those ruffles and have a peak. You will see that there is enough 'flat' fabric between each ruffle to allow you to cut off as many rows of ruffles as you would like. For this dress, I chose to just use one row of ruffles.
It is simple to follow the lines already on the fabric as your cutting lines. Remember, this fabric won't ravel because it is knit. It does, however, have a tendency to curl under once it has been cut. Just be patient, it will all come together rather nicely.
Ta da, you now have a nice row(s) of ruffled fabric with which to embellish your project.