Take off the dead flowers just below the swelling and then leave the leaves alone for 6 weeks so that the energy can go into the bulb to form next year's flowers. You can also give them a good feed - any balanced fertilizer will do, e.g., Growmore, Miraclegro, chicken manure pellets. After 6 weeks you can cut off the remaining leaves; make sure that you brush compost into the hole left to block it and so avoid narcissus fly getting into the bulb.
Treated this way you daffodils will last for years and never need replacing.
To the previous poster, the beetles are pollen beetles and do no harm.