Hello Mahendra,
yes you can set a hostname in the 'crypto map set peer' command insetad of IP address, however, the ASA will resolve that name only once it is applied, hence, it will take the IP that name currently holds, and if it changes, it will not update it.
the easy solution for your case is to use static-to-dynamic L2L configuration. on your ASA, configure a dynamic crypto map, assign it to the static crypto map you have, and then add the pre-shared key to the Default L2L tunnel-group.
an example is given below:
crypto dynamic-map dyn_map set transform-set
crypto map VPN ipsec-isakmp dynamic dyn_map
tunnel-group DefaultL2LGroup ipsec-attributes
pre-shared-key
this way, you must initiate the tunnel from behind the remote device (not your ASA where the dynamic crypto map is configured) and it should work fine.
the document below explains that in details:
http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a00807ea936.shtml
hope that help
Othman