What makes jello melt quickly?

Answer 1

Let's start with the point that what we really mean is, how to cause faster liquefaction, not quicker dissolving which, in the latter case, would mean how to make the dry and liquid ingredients of the Gelatin to go into solution quicker. Uncannily, however, the answer is the same as to either question.

Gelatin is refrigerated or kept on ice in order to prevent its becoming too soft, and eventually reverting to liquid form at "room" temperature. Following from that, the application of heat (that being ambient or artificially applied heat) will, conversely, cause a gelatin's reversion to liquid form (from whence it originated). Accordingly, the process of reversion to liquid will be accelerated by increase in the application of heat, i.e., will be hastened in proportion to the temperature to which the gelatin is subjected.

In effect, the process of preparing a gelatin is reversible.

Answer 2

Hot water and a wisk