Hello!
You could partially rescribe the area - I don't see a real problem mixixng raised and recessed panel lines a little. But if you mean to keep raised panel lines throughout the model, you can re-create the sanded away detail using stretched sprue. You heat some injection frame - sprue - using a candle or a zippo lighter, and when it gets soft, you stretch it until you have a rod of a diameter comparable to the raised panel line. You should remove the whole line (corner to corner) that has been damaged, then scribe a slight groove where the line should be. then you fix the end of the stretched sprue to one corner, wet it a little with lacquer thinner, and put the stretched sprue in the groove. You cut the remainder of stretched sprue with a sharp blade at the other corner, and you're done. To make it stronger, you could add some more lacquer thinner, just don't touch that line until everything dried really well - it becomes very soft. For fixing the corners you could take CA glue. Rivets can also be done - drill small holes, put short lengths of stretched sprue in them and let dry. After that, you can trim the stubs so that they stick out just right, even try to make them spherical by light sanding.
Hope it helps, good luck with your project and have a nice day
Paweł