Generating Headers per Packet[NETWORK]

[Naworia]

I'm working on a project about sniffing packets and sending packets to the game server.
I totally completed sniffing packets and decoding them but there is a problem that If I wanna send same packet to the server, it will disconnect me because I think its about headers. Every time I sent a packet, it changes header of the packet even it has got same datas.

Example :

When I send a messae on chat as "hello"

Packet :

85 DC 80 25 55 9C 34 22 22 E3 39 47 22 E7 39 4E 22 E4 39 22 22

85 DC 80 25 = Headers
55 9C 34 22 = Packet ID & Size
22 E3 39 47 22 E7 39 4E 22 E4 39 22 22 = "hello" message with unicode

And I try to send a message on chat again as hello

1F B7 7E 25 55 9C 34 22 22 E3 39 47 22 E7 39 4E 22 E4 39 22 22

1F B7 7E 25 = Headers
55 9C 34 22 = Packet ID & Size
22 E3 39 47 22 E7 39 4E 22 E4 39 22 22 = "hello" message with unicode

As you saw, Only header changing(it's normal). Problem is I don't know how can I find to generate header for a specific packet

I wanna hear your tips & solutions.

[​Tension]

Looks like a TimeStamp.
Try to find where it gets generated, and recreate the function for it.