Welcome to our community, Barbara
Of course the simplest approach would be to simply save the
image to the folder using the same file name and format as before.
But seeing as how you are changing formats, the next approach is
probably best.
Just right-click the image and choose Image Properties from
the context menu. Then point at the new image. Whatever you had
linked should remain linked and shouldn't be altered. At least on
my PC this is how it works.
Cheers... Rick