Usually brow drop after Botox is from the frontalis muscle (the muscle on your forehead that lifts the brows and creates horizontal lines normally) being over treated. Nicole Kidman, as beautiful and successful as she is, is an example of someone who's frontalis has been silenced.
Most Botox treatments also include the muscles that depress the brow and create the vertical lines between the brows above the nose, commonly referred to as the "11's". If you have been treated in these muscles, then more Botox will not help lift the brows. In the unlikely scenario that these muscles have not been treated then you may get some lift.
Your injecting physician will hopefully know which muscles were injected.
Most likely you will need to be patient for some return of frontalis muscle function to lift the brows.