Anyway to properly alter current list used for a model?
I've gone through 102 Certificate and found that List created previously was not properly configured. e.g. Top Level Item and Parent Hierarchy
After some alteration and re-import the list it ruin my total model and need a re-build from scratch.
You won't need to rebuild the model from scratch, it just depends on the dimensions you have used and how you have linked your calculations and how you've imported your data.
I would suggest checking that the hierarchy items match items within the data file and make sure that they are mapped when you import.
With calculations you need to check that the hierarchy and lists are being referenced correctly.
It may take some time but if you need more help please send some screenshots.
I hope this helps!