The refrain of "Tears, Idle Tears" changes slightly between each stanza, though it is constantly focused on "the days that are no more" (or, in other words, the past). The first refrain, in line 5, prompts the reflections that make up the next two stanzas, because it is the start of the speaker's "thinking." The rest of the poem then goes on to detail these thoughts—to elaborate on what the speaker is actually "thinking" about.
The second refrain, in line 10, then summarizes the speaker's emotions towards the past at this stage of the poem: the past is both "sad" and "fresh." These two adjectives are used to describe contradictory ideas, hinting at the speaker's paradoxical emotions (which will heighten as the poem moves through each refrain).
The next time the refrain appears, in line 15, the speaker swaps in the word "strange" for "fresh." This implies that not much progress has been made towards resolving the speaker's contradictory assessment of the past. In fact, her stance is getting ever stranger, even less logical or coherent.
The final refrain then sums up the speaker's mindset in a paradox: "O Death in Life, the days that are no more!" Instead of resolving her contradictory attitude, the speaker exclaims that the past itself is a paradox when accessed through memories, ending the poem at a sort of midpoint between joy and sadness.