Apparently they kept uncovering sufficient evidence during the surveillance to justify 3 renewals.
"Russia, if you're listening, I hope you'll be able to find the 30,000 emails that are missing," Trump said.
'The U.S. Intelligence Community is confident that the Russian Government directed the recent compromises of e-mails from U.S. persons and institutions, including from U.S. political organizations,' said a joint statement from the two agencies. ' ... These thefts and disclosures are intended to interfere with the U.S. election process.' "
Those “facts” plus throw in some meetings betwen top Trump campaign aids with Russia (one being with Jr. potentially to discuss dirt on HRC with someone interested in ending a sanction that gets in Putin’s crawl), several of whom lied to the feds including about having such meetings in the first place, a firing of the head of CIA over the Russia investigation, and no telling what else we don’t know that is classified, and that is why you get an investigation into the possibility of conspiracy and obstruction of justice.
The IC said : “These thefts and disclosures are intended to interfere with the U.S. election process.”
So Trump asked for interference and Russia interfered.