I have bats that are spending their second summer in my chimney. I did not seal (wherever they come in last Fall) and am wondering that if I do what my chances are of luring them into a new home e.g. a bat house?

Are they only using the chimney in the summer? As long as there are not young bats in the chimney, you may be able to get the bats to use a bat house instead. Unfortunately, they have to find the bat house themselves (baiting the houses has not proven very effective), and it can take them awhile to find the bat house. Unless you need them out of the chimney right away, I'd install a couple of bat houses and then wait until early fall to seal off the area that is giving them access to the chimney. It is best to hire a nuisance wildlife control operator with bat experience to do the work (they can also ensure that bats are not accidentally trapped inside). And then have the chimney inspected to make sure there are no fire hazards. You can learn more about bat houses at Bat Conservation International: http://www.batcon.org/index.php/get-involved/install-a-bat-house.html