Re-treatment is a difficult decision to make especially if the tooth is in a "bad state"!
The decision almost always depends on whether the tooth can be restored (given a crown) with a decent to long-term prognosis or not (after the repeat RCT).
If so, the time and expense of Re-treatment is justified. If not restorable, extract and plan an implant (the best possible replacement) in its place.
Next Steps
Take multiple opinions from Endodontists who do quality work. Post a CBCT or at least an intraoral Xray for more informed opinion.
Health Tips
Heroic attempts to save a poorly restorable tooth are unwarranted. At the same time, extracting a tooth which can serve u in the long run is criminal.