From that description, I'm not sure what's supposed to happen. You'll have to be more specific, maybe show a picture to help
I'm assuming you don't want it to continue where it left off, but to just get back to the path and continue from there?
If so, you can convert the enemy's position into a value along the path's curve. Something like
var value= path_2d.curve.get_closest_offset(position)
And then set that to the PathFollow2D's offset so
path_follow_2d.offset = value
Then just let it continue in whatever method you were using before.