Green’s Dictionary of Slang

to provide with a luxurious standard of living.

1918		‘Bartimeus’ Long Trick 23: They lushed me up to this outfit, and gave me a job as a King’s Messenger.
1936		Wodehouse ‘Trouble Down at Tudsleigh’ in Young Men in Spats 80: Reports of the lavishness of his hospitality [...] might do him quite a bit of good. [...] [A] lover is never wasting his time when he lushes up the little sister.
1960		Wodehouse Jeeves in the Offing 5: He urged me with tears in his eyes to lush Mrs Cream and her son Willie up and treat them like royalty.