Hello Mark615,
What worked for my peace lily before which was in more dire straits than yours, was to put it in shade and kept it moist, watering very well till water gushes out and spritzing the root zone level. The difference is I did not repot then since it was going into Fall at that time.
If that were my plant, I would move it away from direct sun for now, it is in too much stress as it is. Maybe step up watering a bit, depending on the temp around your plant. My peace lily grows well around the 70F range always indoors here in my area since we have terrible dry conditions outdoors, and does like being kept very moist, especially during this past summer season. As typical when seasons start to change, adjust your watering, when Fall starts to come in and temperature around your plant changes, then give some interval. It certainly does not like being too thirsty and dried up.
Recently my plant made its first flower after being in terrible shape and it's bloom has lasted more than a month already. A real surprise for me as well with its resilience.
Good luck, hope your plant recovers nicely. I see good potential on your plant with the new leaf growth showing, so don't lose hope!
Below is a photo of my peace lily to show you how bad mine went first and its recovery:
