Why should I make more SIP investment when my existing SIP investment is making loss?

1. What is the specified period of loss here?
1.1. Let us take the specified period is December 2007 to March 2009.

2. Why this is loss making period?
Since the NAV is falling, in the taken period the NAV has fallen from ₹ 301 to ₹ 117.

3. Why this period is significant for investment?

3.1. In a falling market SIP manages to receive more units.
3.2. For example SIP of ₹ 5,000.00 in 12 December 2007 was allotted 16.59 units, when the NAV was ₹ 301.24
3.3  On the other hand the same SIP of ₹ 5,000 was managed to receive 42.67 units, when the NAV was ₹ 117.16 as on 22 March 2009.
3.4. Hence more units were received on 22 March 2009 on same amount of SIP investment of ₹ 5,000.00 than that of received in 12 December 2007.

4. How we can manage to get more return on investment in a falling market?
4.1. In a falling market if we decided to stop SIP we can manage our valuation as follows:
4.1.1. We stopped SIP after 12 December 2007, and hence as on February 2020, our investment value will be ₹  13,137.95 ( 16.59 units X ₹ 791.92, NAV as on 22 February 2020 )
4.1.2. We did not  stop our SIP, then the valuation of our investment will be calculated on 59.26   (16.59+42.67) units and the valuation will be 59.26 units X ₹ 791.92 = ₹ 46,929.18
4.2. Hence the return on  my investment will be ₹ 36,929.18 ( ₹ 46,929.18- ₹ 10,000.00) which more than ₹ 13,137.95 in a situation when we stopped investment after 12 December 2007.