While I am not certain on the Church’s position on this passage (other than that The Shepherd of Hermas is not divinely inspired), doesn’t this passage clash directly with Matt 18:22 (where Christ instructs that we should forgive one another seventy times seven times)?
I also think that the passage offers little hope for those who struggle with sin to ask for forgiveness again because “it is of no use for such a person for that person will scarecely live.”
Albeit there is some practical sense in trying to ensure that the process of seeking forgiveness is not abused (i.e. that people seeking forgiveness are truly attempting to amend their sinful ways of life), who are we to refuse forgiveness to someone who is honestly asking for it and desiring to follow Christ after much personal suffering and struggle?
Lastly, isn’t the Church a “hospital for sinners, not a museum for saints”? Doctors do not refuse cancer patients who have returned because their cancer came back from remission.
I hope this helps. Please let me know if I have missed the point or anything important, because I have done that a few times in the past.