When you encounter a save point, avoid it. Instead, first kill all the enemies ahead. After your satisfied with the amount of enemies you have killed, backtrack to the save point that was skipped and hit it. The game records your current lure level at this point. Next, after the save point is hit, kill yourself. Therefore when you regenerate at the save point, you will have the same amount of lure. All the enemies that you already killed are back. Kill them again and get even more lure. The Relic Boxes also work in the same way.