Reformatting MacBook Pro without any loss of data

Hello Apple Support Communities,

I am currently experiencing some lag or delays on my MacBook Pro. I was about to result to use any performance utilities out in the AppStore yet I have to result to reformatting. I needed to configure Bootcamp to install Windows (a clean install) here after I have reformatted the MacBook.

Having said the situation I'm in. Is it possible to reformat the MacBook Pro without loosing any loss of data prior to doing the reformat? Is it possible to create a back-up copy within the internal hard disk of the previous running configuration and files? I was afraid to loss some data since there are licencsed applications installed and I've lost the serial key(s).

Thanks,

David