Have you taken a look at the HTTP requests that are made within the browser when going through this manually? You can capture them using Fiddler or the dev tools within the browser you're using. You're essentially just recreating those requests in Python.
Specific to your question regarding lines 51 through 65, it starts earlier at line 39. It seems like you have JSON that's stored in two files. You read the contents from one file, (filein on line 43), and then replace a string, (line 46), and then save it to fileout, (line 48). You then read the contents again on line 52, (you can actually just reuse the newdata variable from 48), and then you de-serialize the JSON into text, (line 55), and then construct the "payload" for the update request, (line 56). Payload data has to be encoded, (line 59), and then you construct a Request object, (line 60), and then retrieve the response from the request, (line 61).
You're not really getting the response of the request, so potentially, there's a problem you're not capturing. You can just print the response after line 61 to see if the request went through. I think you'll see {"status":"success"...} or something similar.
The other thing is take a look at the requests in Fiddler or the dev tools, you may be missing a required parameter. For example, I don't see a token passed along wiht the request, so the response is likely a 498 error, token required. That may be handled by lines 70 and 71, but I don't think that handler is being used if you're submitting the requests yourself using urllib and urllib2. You'll need to provide a token.
