Having such a long crack I would opt to get new bumper cover. Here is site for $285.
2002 - 2005 Kia Sedona Bumper
Alternately, if you attempt to repair your bumper, simple polyester resin and fiberglass cloth (boat repair kit)will probably not do the job. The front bumper on our vans is most likely RIM plastic. Polyester resin will initially stick to the bumper but will release itself as the it shrinks.
Professional RIM bumper repair kits consist of a two-part mix, similiar to hardware store epoxy, one common brand is SEM. There are small kits and larger ones (big as household caulking tubes), one small kit is probably too small and the the other too big. The least expensive repair kit can be found at WalMart near the auto paint supplies. It is called plastic bumper repair kit or similiar made by the Bondo brand. The contents are the same as the SEM professional brand except it is a smaller quantity. The price is right, around $5-$6 and your could get two or three to do your job. You might think about backing the repair up with some metal strap and screws, then filling the fastener holes with the Bondo kit.
Alternately, there are mobile bumper repair people that just fix bumpers, you may want to call one of these guys first for an estimate. The would be able to repair and paint your bumper on your driveway.