Help! External lavalier/transmitter/receiver didn't work. Need to fix up the DSLR audio.

Help! My team's external lavalier mic/transmitter/receiver didn't work. We recorded an entire shoot and only have the audio from the DSLR mic. The talent sounds echoey and distant. A reshoot/ADR is not possible. Does anyone have any tutorials or detailed steps on how to use Adobe Audition to make it sound like it's coming from the lav? Any help is much appreciated!!