How it is determined to have BCG treatment depends on risk stratification which depends upon the grade but also other factors. For NMIBC, the classification is low risk, intermediate risk, high risk. Any high-grade tumor is classified as high risk. Even it is low grade, it is classified as the intermediate-risk if the tumor is greater than 3 cm, it has multiple tumors, or if the tumor is recurrence.
TaLG - single, < 3 cm, the first time is considered low risk
TaLG - multiple, and/or > 3cm, and or recurrence is considered as intermediate risk.
TaHG, T1HG, CIS - are considered high risk
Above risk stratification is the result of a large study (2,600 patients) done by EORTC (European Organisation for Research and Treatment of Cancer) which was published in 2006. It resulted in a simple risk calculation table.
I have listed a link to the risk calculation.
In a low-risk patient, a clinician should not administer induction intravesical therapy. (Moderate Recommendation; Evidence Strength: Grade C)
In an intermediate-risk patient, a clinician should consider administration of a six week course of induction intravesical chemotherapy or immunotherapy. (Moderate Recommendation; Evidence Strength: Grade
In a high-risk patient with newly diagnosed CIS, high-grade T1, or high-risk Ta urothelial carcinoma, a clinician should administer a six-week induction course of BCG. (Strong Recommendation; Evidence Strength: Grade
Please note that these are guidelines and clinical doctors may choose a slightly different treatment based upon his or her clinical experience and other evidence.
AUA guideline explains that long-term follow up of low-grade Ta lesions demonstrates a recurrence rate of approximately 55%, but with a much lower percentage (6%) experiencing stage progression.
So, if the original diagnosis was that it was a single tumor, no CIS, LG, < 3cm, then even the recurrence puts you to the intermediate-risk category, because it happens once 5 years later, I incline to think that your urologist will not put you on BCG and put you on surveillance by regular cystoscopy. But it is possible to treat you with one time intravesical chemotherapy to reduce the possibility of future recurrence.
Risk calculation table
www.evidencio.com/models/show/1025
Please note that the current grading system (LG,HG) came out in 2004 by WHO. Prior to (LG,HG) grading system, (G1,G2,G3) rading system was used and even today some urologits contitue to use old grading system, ie. my urologist. G2 is considered in between LG and HG.
AUA (American Urological Association) site on the guidelines for NMIBC
www.auanet.org/guidelines/bladder-cancer-non-muscle-invasive-guideline 
