Goalkeeper Lee damaged ligaments in a shoulder after falling awkwardly during the Johnstone's Paint Trophy victory over Oldham on September 4 and it was thought the injury would keep him out for up to eight weeks.
A similar timescale was put on Smith's recovery from an ankle operation after the left-back went under the knife that same week.
Striker Richards suffered an ankle injury in the thrilling 4-3 home league win over Accrington on September 18. Last week scans revealed the damage was not as serious as first thought and the 30-year-old was expected to be unavailable for around a month.
Caretaker manager Tommy Wright said: "They are all progressing well but we have to be careful with them in case one of them has a setback. But I would say, fingers crossed, they are probably just ahead of schedule.
"We are pleased with their progress but obviously, as I said, you can have setbacks. At this moment in time we are really pleased and hopefully they will keep progressing."