When you do a resident load from a previously loaded table you should get everything in that table unless you have not specified all of the fields to load. That said unless you modified some fields in the original load.
When I do that I find that it is better to store the first table in a QVD and then Load that QVD in the next step to do the calculations and other changes.
Can you provide more details?
I hope you're trying something like this ,
Sum(B) as Total,
group by A;
if you try to add like above , QLik throws error as you can't add C which is not in GROUP BY Clause.
if you need to use all the columns from Source table and you want to use GROUP BY ,
you need to add all cols in group by clause (OR) do the aggregation and perform the Outer Join to Source table to get all the fields.
Hope this Helps