Evaporation three times as taught in Hokes book, will normally remove the nitric acid.
Adding a bit more gold while concentrating the solution to use up nitric in dissolving the added gold.
Sulfamic acid to convert the excess nitric to sulfuric acid in solution.
(limiting nitric use in the beginning, leaving a little undissolved gold)
I will normally use a combination of the above methods to eliminate the nitric from solution, or to be sure that I have removed all of the nitric, but of course if I limit my nitric use from the beginning it makes it much simpler to remove any remaining traces.
The stannous chloride test will not work if there is free nitric acid in solution. A positive stannous test where the gold is reduced to colloidal gold in solution, is a good indicator that most of the excess nitric acid has been eliminated from solution.
A prill of urea fertilizer to see if it fizzes to check for nitric.
If we had much more Nitrate salt (or nitric acid) compared to the amount of HCl in the reaction we could create a situation where the nitrate or nitric will not be consumed in the reaction, or the nitrate salt is not converted to HNO3 in solution. (I am unsure of how to say this).
If you had Excess or too much NaNO3, and it did not all dissolve, I would tend to wonder if the HCl in the reaction was consumed by the reaction with NaNO3 and gold, if so you may need more HCl to convert remaining NaNO3 to HNO3, (but here then the solution would hold more gold).
Bit late now, maybe next time try dissolving the nitrate prills in a water boil before hand can help to get the sodium nitrate prills dissolved to a thick nitrate salt water solution which could be slowly added in small proportions to the HCl and gold, this may help in not over use of the NaNO3 in solution.