Will NPC respawn if I delete them All?

I cannot stand the current way the NPC all gather by the shoreline. Hundreds of them all grouped up. I want to redistribute them and get them to act normally, ie Cows stay in the fields and Moose in the forests. Some how now all the NPCs group together and slowly start to congregate downhill along the shores and rivers in huge groups. How can I delete them all and start over? I use the deletenpcs command but that is tedious and the distance is general not to mention cows not bulls are deleted or brown horse not black ones. There needs to be a better way to make it look realistic in game.