Im upgrading my trolling motor from 12v to 24v and Im not sure if I can wire in the plug shown in the picture from my old troling motor or do I need to buy another thats for a 24v system? thank for the help in advance.

Back at your batteries you will need to change how they are wired. As far as I know you won't need to change the plug in the pic.

For a 24v system you need two batteries of course. If you want it to remain a 12V system wire the batteries in parallel (pos to pos / neg to neg). I had a 12v system on my first boat and added a battery and did this. It would last all day.
For 24v you need to wire it in series (Batt 1 neg to Batt 2 pos / batt 1 pos to batt 2 neg). Wires to your plug will be pos from batt 1 and neg from batt 2.

I hope someone will verify this as correct. I'm 90% sure i'm right on this.

NO.....Series is Batt 1 neg to Batt 2 pos and Batt 1 pos to TM and BATT 2 neg to TM.

Really should change the plug and receptacle to at least one that's rated for a minimum of 30 amps and 3 pronged, and preferably a twist lock. The wiring will need to be re pulled with a minimum of #8 preferably #6, if it's not that already. Here is a basic 12/24volt wiring diagram. When you replace the plugs and whether you have a 12/24v combination or straight 24v this will work. On the straight 24v there won't be any plug termination from the Trolling Motor to the 12v terminal in the receptacle because those motors are only a 2 wire.

Look up the manual for the year and model. I was wired for 12/24v and the tm that I was installing was 24v only but it had 4 wires. When I contacted MK, that particular motor only required one each pos and neg wire from the battery but each of those had to be wired into double wires at the tm. I almost wired it 12/24 by mistake before calling MK tech support

Thanks guys for the help

If you want to use the same plug, take it off the 12v tm and wire it on the 24v tm.

I wouldn't use the same plug. I would go with a plug that allows the wiring to be directly connected without the use of crimps. This way, you keep the same size wiring all the way to the plug and between the trolling motor, plug, receptacle , and trolling motor wires you only have one connection (instead of three) that is considered a high resistance connection (plug). As stated before, 6ga is better and in some instances 8ga will work.
John