Dividing med bulbs?

Ten years ago I planted lots of bulbs of various spring and summer blooming flowers. For the last five years, my house has been let to tenants who couldn't find pruning shears if they were tied on a string and hung around their necks. This resulted in many of my flowers not getting much sun, if any. Now that spring is on its way, I have noticed that the bulbs are producing lots of foliage, but very few buds. I need to divide the bulbs this summer after the foliage dies away, but I am wondering if it is a good idea to do so after a "recharging year" -- will I destroy my chances at flowers next spring?