oristarA > I don't understand why "last" is used here. It seems useless and should be removed since you've unambiguously referred to the April and July this year... "We're doing very well with respect to making the turn on the pandemic," Trump declared again on Friday, comments he made last April and again in July..."
You're right—it's unnecessary. "In April, and again in July" would've been fine.
English is a very efficient language. When you see a multilingual sign, notice how much shorter the English version of the text is than the other languages (except some Asian languages, whose logographic format is even more compact). For that reason, English writers and speakers often use more words than necessary—they feel like they haven't worked hard enough to express themselves.
Even professional writers often use unnecessary verbiage, especially when they're under deadline or expected to submit a minimum number of words. It's the copy editors's job to catch that, but no one's infallible.