。
She's probably just overdoing things again, as usual.
Literal
She [topic-は] probably again things [object-を] more-than-necessary [excessively-過剰に] [is-doing-行っている] [it's just-だけです].
Two near-synonyms for 'in excess' stack: 必要以上に ('more than necessary') and 過剰に ('excessively'), each adding a layer of emphasis. This kind of doubled hedging or amplification is fairly common in Japanese expository prose, where a writer wants to drive a point home without strong vocabulary. 行う (おこなう) is the formal/written counterpart of する ('do, perform'), giving the sentence a slightly stiff, evaluative tone — the kind a friend or colleague might use when half-affectionately diagnosing someone else's behavior. ~ているだけです softens the judgment to 'is merely / is just,' framing the criticism as observation rather than condemnation.