Greetings,

after Japan and Germany i am now playing the UDSSR.

It;s 41 and germany just attacked me, now i have the following problem...i stil have a peace time IK-debuff, i could
remove him with the "Great patriotic War"-Event but for the Event to start i have to loose a number of provinces.

Now...i am holding the line imo and pushing forward in Romania.

Is there any way to remove the debuff or start the Event without losing those provinces?

That event is meant to simulate the economic mobilization of the Soviet Union after the invasion of Germany.
Since in your case the invasion was unsuccesful, there's no need for the SOV to take such drastic measures.
Therefore you cannot take that decision (without cheating).

That's not completly right, the economic mobilisation had started with the 5year plans and was progressing.

It was a very fast change to Wareconomy and more important, while a bit simple phrased, allowed Stalin to "unite" the people against a common enemy and "heal" some of the problems the purges caused.

I am playing a long session, lasting up to 1968, so it will most likly include a War against the Nato.
"The Great patriotic War"-Event does not give a buff, but removes a debuff that gives a additional drawback against the USA, every IC i produce myself is only 0,7 IC...

If there's a way to remove the buff on a slow way to simulate a slow change to Wareconomy fine but never being able to remove the debuff isn't fun.

I am sure i will still win, it just feel wrong.

The event Great Patriotic War fires even if you're at war with USA, ENG or FRA, so it will still fire in a war against NATO, but again only if you're losing territories. This is how you remove it, so it's not true that it's never possible to remove it.

You've obviously already deviated greatly from history by not losing territory to Germany, so you probably do not need this debuff even against the USA. IMHO it makes sense to happen only if you're losing.

Given the fact that you're planning a campaign that deviates greatly from history, my best suggestion is to learn how to create events in DH, so that you create your own story. In this way you can create multiple events that let you increase this modifier gradually, maybe giving a choice of whether to do it or not, including possible negative effects and/or random events that may or may not fire based on your choices.
If you don't want to do that, you can at least simply fire the event using the console.