Blocked wells prompt new avodah

וכמ"ש כבר בעשרה רעבון שכ' במדרש ובפסוק וכל הבארות כו' שחפרו בימי אברהם.

As was already written regarding the "ten famines" mentioned in the Midrash, and on the pasuk "and all the wells... that they had dug in the days of Avraham."

The Sefas Emes connects an earlier teaching about the ten famines to the wells of Avraham that the Pelishtim later stopped up (Bereishis 26:15).

פי' בהארת הימים של אברהם אע"ה חפרו אותן הבארות.

Meaning: through the illumination of the "days" of Avraham our father, peace be upon him, those wells were dug.

The "days of Avraham" refers to the spiritual light radiating from his days; it was by that light that the wells of living water were uncovered.

וגם ימים ממש כמ"ש כמו שהם תמימים כך שנותיהם תמימים.

And also literal days, as it is said, "just as they themselves are whole (tamim), so their years are whole."

The phrase also means actual days: because the Avos were perfect and whole, their very days and years were complete and unblemished (cf. Bereishis 24:1, "Avraham came with his days").

ואח"כ נעשה רעב וסתמום פלשתים כדי שיחפור יצחק דרך חדש.

And afterward a famine came, and the Pelishtim stopped them up, so that Yitzchak would dig a new path.

The wells were deliberately blocked and a famine sent so that Yitzchak would have to open a fresh channel of his own - his own avodah rather than merely inheriting his father's.

וכמו כן נמצא מזה בכל פרט וד"ל:

And likewise one finds this in every individual, and the wise will understand.

This pattern repeats in every person: the spiritual "wells" opened by earlier illumination may become blocked, precisely so that one is forced to dig a new path and renew one's own avodah. A hint to the wise is sufficient.

Summary: The wells dug in "the days of Avraham" were opened through the spiritual light of his perfect days. They were later stopped up by a famine and the Pelishtim specifically so that Yitzchak would dig a new path of his own - and this same pattern recurs in every individual, whose inherited channels of holiness may become blocked precisely to prompt the renewal of his own avodah.