In 1928 Beiyang government was replaced by the Nationalists, with its last leader, Zhang Xueliang, agreeing to submit to the Nationalist government. But did any warlord cling to the symbols etc for legitimacy after that?
After the Nationalists consolidated power in China in 1928, their government promptly received international recognition. Therefore there was little reason to claim descent from the Beiyang regime.
All except Japan, that is. Due to having poor relations with the Nationalists and harboring ambitions in China, they set up puppet regimes and adopted Beiyang symbols to boost their legitimacy. Note the similarity in flags, for example:
So no, no Chinese warlord used Beiyang symbols after 1928; only Japanese puppet regimes did.