Help securing a software that is no longer developed but is still usable needs more security

Hi I have a license for an old software chat system that is no longer developed but is still usable, it recently got hacked and there are a lot of exploits where hackers can get the names and passwords of the users, I would like to see if some one could improve this software for security and stability it is called chatspace 4.0 and is made with java and c it has a web applet so users can connect via web page, and also users can connect to the chat server with mirc, With this chat been a source of my income I am low on funds and would like topay around $8 per hour 1 hour per week if that would be possible, if it could be looked at and broken into stages I could pay per stage of each hour ect,