The full title of this poem is: "Lines Composed a Few Miles above Tintern Abbey, On Revisiting the Banks of the Wye during a Tour. July 13, 1798." As such, it is an incredibly descriptive title which gives us significant insight into where and when Wordsworth wrote this poem, and what inspired it.
The title of the poem does not suggest that Wordsworth intends to write about Tintern Abbey itself. Rather, it tells us that it was a visit to the Abbey which inspired this outpouring of contemplation on the sublime in nature. The speaker notes that "five years have past" since he last beheld "these steep and lofty cliffs," and, as such, he is able to consider with new eyes the "thoughts of more deep seclusion" which are prompted by the favorite landscape. The speaker sits "under this dark sycamore" and gazes out across the cottages and orchards, the quiet sky, and recalls how, "in lonely rooms," the memories of these views have helped him recall "sensations sweet," an "aspect more sublime."
In revisiting Tintern Abbey, then, the poet is inspired not only by the view itself but by the memories of how this view has sustained him when he has been away from it. Wordsworth ruminates upon how often his "spirit turned to thee," this view of the River Wye and the landscape around the Abbey, a picture in his mind which served as a fount of inspiration for him. The title of the poem does not, perhaps, illuminate the reader as to the precise theme of the poem—emotion recollected in tranquillity, as Wordsworth said in his "Preface to Lyrical Ballads"—but it aptly describes the precise time and circumstance in which the poet wrote, and details the scene which was his inspiration.