Here are some sources. I can't find more atm, so they are only examples.
1. Gazeta Gdansk, 9th of October 1925: "Poland must insist, that without Königsberg, without all of East Prussia it can't exist. We must demand in Locarno, that all of East Prussia is to be liquidated... If this isn't possible on a peaceful way, then a second Tannenberg will come."
Someone on this forum told me some time ago, that this was a right fringe newspaper. But it was indeed near to the government. A Pilsudski near newspaper I don't know this moment said, in a sense, that East Germany had to be annexed in a war, where "no prisoners are made" and "without any humanity". I had to look after the exact source. But that needs time I don't have just now. It shows nevertheless the intention of the Polish government in this time.
2. Roos, Polen und Europa, page 38: In October 1931 Marshall Pilsudski tells Hoover, "Poland had to invade Germany to clear the things once and forever". This was indeed an attempt to press the USA not to change the Versailles treaty, but still shows bad intentions towards Germany.
3. The quote I gave in my first post here is from: Akten zur Deutschen Auswärtigen Politik, Series C, vol. I, Document 22. This was from February 17th 1933. At the same moment there were three attempts to convince the French to attack Germany. Sources for this: Historic Commission of the Polish Staff (Polish), Vol. 1, Part. 1, London 1951 and Stanislaw Mackiewicz, Beck's Policy (Pol.), Paris, 1946.
4. Some postcards:
Both are propaganda pictures of early 1939. Similar existed before.