If TSL is hit and NF goes below the "Buy Above" and comes back again, My suggestion is to take a second entry. Reason is , The second entry may cross all the 4 targets without hitting the TSL again.
Another way of trading by GANN values would be to revise the SL's to the Targets .
Example :
Nifty Fut 9.30 close 4771.2
Buy above 4778 Stop loss 4761 target 4793 4810 4828
Sell below 4761 Stop loss 4778 target 4746 4729 4712
Lets take today's Buy Above , which was 4778 , Assume that the first target is crossed , i.e., 4793, As soon as 4793 is crossed , revise the SL from 4761 to 4778, And assume that NF goes still further to the second target 4810, Immediately revise the SL to 4793 and so on.
I would like to add here that at the end of the day , all the strategies give almost similar returns. Only thing that is needed is to stick to any particular method and have strict money management, and military discipline.