Reuse Class update methods in project

Hello,

I have an OO question.  I want to have a common reuse class.  I have this reuse class in multiple projects.  Lets say I add a method to the Reuse class.  How do I get the new method into the projects that use the reuse class?  Do I have to manually add the method to my class in every project that uses the reuse class?  Is there way of automatically loading classes from file that may have methods added to them?

Thanks