My favourites are
Bethan (also a name in its own right nowadays) and
Libby and also
Lisette
Another Welsh nn is Betsan
Also heard of:
Lilias and
Lillias - Scottish names derived from
ElizabethLylie - used in 19th century Ebgland as a nn for
ElizaTetty (Dr Johnson's wife
Elizabeth's nn, not used much sine the 18th century -
Totty was used for
Charlotte)