If, upon the hearing, there appears substantial ground for apprehension, the approving officer or board may order the principal to give a new bond and to supply the place of the petitioning surety within a reasonable time to be prescribed, and, upon such new bond being given, the petitioning surety upon the former bond shall be declared discharged from liability on the same for future acts, which order of discharge shall be entered in the proper election book, but the bond will continue binding upon those who do not petition for relief.