Ideas on how to debug.

Anybody got any ideas on how to make a change in python code and not reload the whole UI again. Context: I have an app that has steps. Step1 over, go to step 2, step3 over go to step 3. and so on. So if I have reached step3 and the function (API) I call in python (via a button click in UI) throws an error, after fixing it, I have to reload the whole server, that means again going through the process of completing step 1 and step2 and finally reach step3 to see if the changes i made work correctly or not. Is it possible to reload only the python code and not the UI.