How to amend application if pleading stage complete in Arbitration?

See when it comes to Arbitration, the Code of Civil Procedure is not applicable to the same. So even if the pleadings are completed, there is no express bar with respect to amendment of the pleadings. 

It is a general rule that once the proceedings have reached the stage of evidence (examination and cross-examination of witnesses), the Court / Tribunal shall refrain from allowing the amendment applications unless sufficient cause is shown by the Applicant for filing the Amendment Application.

We will be in a better position to guide you if we could know as to which forum this application was moved which you are seeking to amend. Is it an application before the High Court or before the Arbitral Tribunal?