Edit Tweepy-based python script in order to archive more data from a private account on Twitter

Hi all, I'm trying to archive all the tweets using a python script I found on github on a daily basis. It's working well except that at around 6500 rows, old data starts getting removed and replaced by new data. Note that the private twitter account I want to archive tweets from has a very high tweet output, to the tune of 1000 tweets a day. I have the script automated to run every night, but the issue is as stated above in that it hits an approximate max limit and starts overwriting old data. I cannot figure out why it's happening based on the script, although I am a novice at programming. This script uses Tweepy - [login to view URL] TASK: 1. Fix script so it continually adds to the output .csv instead of overwriting data 2. Change script so output does not contain HTML If you have an entirely different solution that serves the same purpose that would be okay too. Python file is attached with sensitive info removed.