http://theryanmcgrath.com/ Another good site for reading interviews on A-list copywriters, among other articles there.
Well, sometimes instead of reading advice sites and copywriting books, it is best to relax and do fun/interesting/exciting/refreshingly different things (Not part of your usual routines) like going somewhere or doing something or engaging in some activity or talking/hanging out with someone you usually don't talk to/hang out with. It could free your mind, give you new ideas and help you write better.