How to get the input variables while calling same callActivity and changing the variables

I have a sub process “BreakPoint” call activity, which I need to call multiple times, while passing the different value of my variable “FileStatus”, at first time, its getting the variable but next time its giving me null. As the functionality is same just need to get a changed variable at next stage.

Let me know why I am getting null to my input variable next time and how to solve my issue, otherwise I will have to create duplicate call activity with duplicate tasks.