The simplest way would be to just create a new droplet based on that image. If you're going to make it a clone of drop1, it will wipe all of the data on drop2 either way. If you really want to repurpose the existing droplet, you can do this by rebuilding the droplet based on the snapshot.

In the DigitalOcean control panel, go to Destroy > Rebuild and select your snapshot in the drop down list. Then, click the Rebuild from image button. It looks like this.

Your droplet will now be rebuilt based on the snapshot. Remember this will delete all information that was originally on the droplet.