[SuperViper]

Change your timer to

pawn Code:

public ResetJumping(playerid)
{
    SuperJumpEnabled[playerid] = 1;
    SetTimerEx("ResetJumping", 2500, false, "d" , playerid);
    return 1;
}

Also, remove

pawn Code:

SetTimerEx("ResetJumping", 2500, true, "d" , playerid);

from your command.