"Is the same as" is ambiguous. It could mean "same thing" or "same kind of thing" or even "same thing but not necessarily same stuff". Your father is speaking in the last sense--the glasses look the same, and moreover, the 3 pairs of glasses are built through successive fixes. You can avoid the verbal paradox by asking "the same in what respect?" The glasses are not the same stuff, and they do not have all the same physical properties (such as weaknesses in the glass and frame) but they are the same style and they are constructed successively out of one another.

If the alternatives are living in the past and living in the future, we can only live in the present. If the alternatives are thinking about the past and thinking about the future and thinking about the present, we have choices. "Living in the present" is a cognitive psychological technique used, often successfully, by those who brood about the past or fret about the future. Concerns with the past or future may be appropriate (e.g. someone regrets a romantic choice or gets a worrisome medical diagnosis) or inappropriate (due to anxiety, excessive guilt etc); the technique works for all of them. Many people report that it helps them live a fuller and calmer life. For those who suffer from poor impulse control or psychopathy, however, it might be better to focus more on the future and the past and less on the present.