I am not able to see the increased memory and the any errors after the nodejs is running after 4 or 5 hours.
If you are using a OS that supports dtrace you can use it to debug memory leaks in running processes.
http://dtrace.org/blogs/bmc/2012/05/05/debugging-node-js-memory-leaks/
If your OS doesn't support dtrace you can setup a Joyent SmartMachine very cheaply just for debugging.
http://www.joyent.com/products/joyent-cloud/pricing
Without more information or looking at your code it is hard to say exactly what could be the problem.