I don't see why you have to change it if it's working.
If you have done this for 8 weeks ( just estimating ) and you feel like your still making progress then you should take a week and redo your 5RM and recalculate your lifts , then start over again . This time you will be lifting heavier weight.
Make sense ?
Unless you are board with the program , which I can't see if your making gains