Is there a cleaner way to write these if statements?

The following code reads a file, splits its data, replaces some characters in the data, and then joins the data again:

fs.readFile(filename, 'utf8', function(err, data) {
  if (err) throw err

  data = data.split('\n\n')
  var tree = data.slice()

  for (var i = 0; i < tree.length; ++i) {
    if (tree[i].match(/^#/g)) {
      data[i] = data[i]
        .replace(/^#### (.*)/gm, '<h4>$1</h4>')
        .replace(/^### (.*)/gm, '<h3>$1</h3>')
        .replace(/^## (.*)/gm, '<h2>$1</h2>')
        .replace(/^# (.*)/gm, '<h1>$1</h1>')
    }

    if (tree[i].match(/"|'/g)) {
      data[i] = data[i]
        .replace(/"(?=\b|\*|')/g, '“')
        .replace(/"(?!\b|\*|')/g, '”')
        .replace(/'(?!\b|\*)|(?=\b)'(?=\b)/g, '’')
        .replace(/'(?=\b|\*)/g, '‘')
    }

    if (tree[i].match(/--/g)) {
      data[i] = data[i]
        .replace(/\b--(\b)*/g, '—')
    }

    if (tree[i].match(/\*\*|\*/g)) {
      data[i] = data[i]
        .replace(/\*\*([^\*|\s]+)\*\*/g, '<strong>$1</strong>')
        .replace(/\*([^\*|\s]+)\*/g, '<em>$1</em>')
    }

    if (tree[i].match(/^[^#]/g)) {
      if (tree[i - 1] && (tree[i - 1].match(/^#/g) || tree[i - 1] === "* * *")) {
        data[i] = '<p class="ni">' + data[i] + '</p>'
      } else {
        data[i] = '<p>' + data[i] + '</p>'
      }
    }
  }

  data = data.join('\n\n')

  saveHtml(data)
})

Example input:

# Title

'Single quotes'

"Double Quotes"

* * *

Paragraphs

Output:

<h1>Title</h1>

<p class="ni">‘Single quotes’</p>

<p>“Double Quotes”</p>

<p>* * *</p>

<p class="ni">Paragraphs
</p>

Is there a cleaner way to write those if statements? Or at least create a function so that there is less code in that fs.readFile block?