174 pg/mL is mild deficiency, not the severe range - so oral is enough for you. Injections are needed only when levels are very low, or there is numbness/tingling, anaemia, or a gut absorption problem. Two Neurobion Forte a day for one month will barely move the needle though; the effective dose is methylcobalamin 1500 mcg daily for 8-12 weeks, then recheck. Also worth checking why it dropped - vegetarian diet, long-term antacids/metformin, or
B12 loss from the gut.
Next Steps
Start oral methylcobalamin 1500 mcg once daily and repeat
B12 with CBC after 3 months. Ping me on Practo with your CBC and symptoms if you want the dose and duration fixed for your case.