Update!!!!!
I have 2 paradoxa plantlet from the leaf that lay flat in spagnum moss. hurray!!!
For water method, Drosera that produce plantlet is,
D. intermedia 'cuba' --> all leaf produce plantlet, each leaf have 1 ~ 3 plantlet
D. binata --> 1 out of 2 leaf produce plantlet, each leaf have 4 plantlet
The most happy success story is --> D. paradoxa!!! I have 2 leaf in water and 1 produce plantlet!!!
D. intermedia 'cuba' leaf in water
D. paradoxa