"There is more than one way to do it" ™ depending on your use case.

The "problem" is not that you can't repeat a pattern in Perl, but that only the last captures are kept for explicit (...) groups.

One way is a code section to store the current capture groups.

Another to create explicit captures.

 DB<25> $_='1016.1 7.7 NaN -20.6 3.8 72.9 215.0'

  DB<26> $pat = qr(NaN|-?\d+\.\d)

  DB<27> x m/($pat)/g
0  1016.1
1  7.7
2  'NaN'
3  '-20.6'
4  3.8
5  72.9
6  215.0
  DB<28> x m/($pat)(?:\s|$)/g
0  1016.1
1  7.7
2  'NaN'
3  '-20.6'
4  3.8
5  72.9
6  215.0
  DB<29> x (m/($pat)(?:\s|$)/g)[0..3]
0  1016.1
1  7.7
2  'NaN'
3  '-20.6'

...

  DB<33> x m/(?:($pat)(?:\s|$)){4}/
0  '-20.6'
  DB<34> x m/(?:($pat)(?:\s|$)(?{push @a,$1})){4}/
0  '-20.6'
  DB<35> x @a
0  1016.1
1  7.7
2  'NaN'
3  '-20.6'
  DB<36>   
...
DB<47> $delim =  '(?:\s|$)'

  DB<48> p $explicit=  "($pat)$delim" x 4
((?^u:NaN|-?\d+\.\d))(?:\s|$)((?^u:NaN|-?\d+\.\d))(?:\s|$)((?^u:NaN|-?
+\d+\.\d))(?:\s|$)((?^u:NaN|-?\d+\.\d))(?:\s|$)
  DB<49> x m/$explicit/g
0  1016.1
1  7.7
2  'NaN'
3  '-20.6'
  DB<50>
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