Your other option is to use more loops and only put the output lines in the loop where you want the values, so something like:
BATCH
DT,,dt
TRANs,newm
MASS
LOOP,,n1 ! Loop n1, where dt*n1 = t1
TIME
LOOP,iter,1
UTAN,,1
NEXT,iter
NEXT
LOOP,,n2 ! Loop n2, where dt*n2 = T
TIME
LOOP,iter,1
UTAN,,1
NEXT,iter
stre,node,1,1268
NEXT
LOOP,,n3 ! Loop n3 to finish
TIME
LOOP,iter,1
UTAN,,1
NEXT,iter
NEXT
END
The if-else-endif method is cleaner; this is just another option.