Always stick with the basics as much as possible. They should remain the core of your program.
When you see an issue of not continuing to make gains, then you need to analyze what is happening. You may be stalled for a number of reasons.
You could be tired and need a few days rest, maybe even a week.
You may need to deprioratize the core lift and work on the synergist muscles, and bring them up to strength some more.
You may just need to drop your weight back, and do one of two things. Alter your rep range from your current scheme, or just take another run at the weight you find your self stuck at. The deload may be just enough to let you catch your breath, so to speak.
Maybe you need to eat more.
It may also be that only one lift is stuck, but you still progressing on the others. This is definately not the time to abandon your whole routine. Small tweaks are needed. Don't throw the baby out with the bath water.
Patience is always needed in this sport. Progress is measured in weeks, and months, not hours or days. One rep or one pound is progress.
Personally, I think that if you keep progression as the focal point, that most people can use the same routine for a long time. This notion of you need to change every 6-8 weeks is kinda absurd. Simply swapping the way you order you moves per sesson can be a huge difference on how your workout go's.
I think an important aspect is being able to analyze for yourself and see whats needed. If you can do that, you should be able to go for years with small course changes along the way.