I think you’ll be able to keep improving with practice!
There are no shortcuts to speed so you’ll need to be able to play at 81-99 BPM before you’ll be able to reach 100 BPM.
I recommend checking out the practice tool “The Amazing Slow Downer” which allows you to adjust the speed of any mp3.
This will allow you to find the exact speed you need to work on and gradually increase the speed over time.
I highly recommend the software. I use it all the time in my daily practice. If you have any other questions let me know.