I believe the Decision Point Procedure fuel requirements is based on the applicability of a decision point for drift-down purposes (over the Alps etc.). When your net ceiling is such that a decision point is required you must then take into account an enroute alternate and adjust fuel accordingly. The reclearance procedure should be as defined by fireflybob.
The decision point is defined in JAR OPS. Basically it applies when your net ceiling is less than 1000 ft above the highest obstacle. The DP must provide you with at least 2000 ft above all obstacles during a driftdown situation. Engine fails before the DP you proceed to the enroute alternate.
For fuel planning, apply as written in the OM.
Regards,
Darren