I think you mean that imported scripts are not reloaded after you change them. Is it so? If it is, there's one reason. To speed things up, the interpreter just parses imports the first time, and then uses the previously-generated code to run the module again.
Luckily, you can use Python's reload() function to fix this. Remember to remove that function in your final script, so that the code will not have to be regenerated every time.
I hope this is helpful.
for Robert McNeel & Associates