तो क्या हुआ , जो एक ट्रेन निकल गयी तुम्हारी, जिंदगी के ट्रैक मे अगली ट्रेन भी आएगी। - karthik

As sooner or latter no new trains will be introduced in routes you have mentioned. I would be happy to see if Uttarbanga / Kanchankanya / Teesta-Torsha / Kanchanjunga Express are augmented with more coaches. Hope this rests with ER.
.
The very important factor which i see is Railway Electrification in this section. With railway electrification, powerful 6000+ Hp engines can play in this route & speed of the train[passengers+goods] will increase. 2nd will be track doubling.
....
more...

Other then that Railway should introduce 6000+ Hp diesel locomotive. 6000 hp diesel locomotive is already being designed buy EMD for China Railway [China Railways HXN3]. RDSO should try to implement this type of locomotive here in India also.
.
16 cylinders in a V configuration
Up to 6,300 bhp (4,700 kW) at 1000 rpm (eq. 33,000+ ftlbs torque)
265 mm (10.4 in) bore
300 mm (11.8 in) stroke
1,010 cubic inches (16,600 cm3) displacement per cylinder[1]
Twin turbochargers
.
Source:click here