Seems to me like you are well on the way to improving your rep just by what you've been doing....but TALK ABOUT the great things your chapter and it's members have done/are doing to ANYONE WHO WILL LISTEN !!! It's not just one person's responsibility to improve the rep, although a good public relations rep can help spread the word about the good things you are doing.
Social wise... Just keep calling and calling and calling... and have ideas in mind for themes and what to do when you call. If you have some idea and help plan and call them and say "we would like to hold a _____ social with your fraternity on _____ date..." you're much more likely to get a response/have an event than if you call and say.. "our houses need to have a social"
