The phrase "miss you any harder" implies that the speaker is already experiencing a deep yearning and longing for the person, suggesting that their feelings are already quite intense.
The playful notion that "my heart might come looking for you" adds a whimsical and affectionate touch to the statement. It suggests that the speaker's heart is so connected to the person that it might metaphorically seek them out, highlighting the depth of their emotional attachment.
In essence, this statement poetically conveys the idea of profound longing and emotional connection. It humorously suggests that the intensity of the speaker's feelings is so strong that it feels as if their heart is actively seeking the person they miss, emphasizing the depth of their affection and attachment.