Blackwell retained her position in the national team for the Rose Bowl series, which consisted of three matches each in New Zealand and then Australia. She played in only the third match in New Zealand and did not bat in the seven-wicket win, before being omitted for the first match at home. She was recalled for the second match and made 15 not out in a 40-run win, before her unbeaten 22 guided Australia to a four-wicket win in the final match at Bellerive Oval, as the hosts took out the series 5–1. In the first four matches of the 2004–05 WNCL, Blackwell made 54 and 27 in her only innings as the opposition bowlers failed to penetrate the New South Wales top-order in the other two matches. The defending champions won all four matches before the season was adjourned when the national team travelled to India in December for seven-match bilateral ODI series. Blackwell scored two in a 14-run win in the opening match in Mysore and was dropped for the next match. She was recalled for the third match in Mumbai, run out for a duck in a six-wicket defeat. The tourists won the next two matches to seal the series, but Blackwell was not prominent. She was not required to bat in the third match and was run out for 13 in the next. She made 19 in the sixth ODI and was dropped for the final match of the tour, ending the series with 34 runs at 8.50. Blackwell returned to Australia needing a strong end to the WNCL season to ensure selection for the 2005 World Cup in South Africa. In the four remaining round-robin matches, she made 96 runs in four innings, half of these coming in a five-wicket win over Queensland. New South Wales met Victoria in the finals. Blackwell was not required to bat in a seven-wicket win in the first match before making 13 and 24 as the reigning champions were dismissed for 71 and 109, losing the last two matches by five wickets and 50 runs respectively. Blackwell ended the season with 214 runs at 26.75 and this was enough to secure retention in the national team despite her poor results during the Indian tour. The Australians hosted New Zealand for three Rose Bowl ODIs in the western coastal city of Perth before the teams crossed the Indian Ocean to reach South Africa. Blackwell was not productive in the trans-Tasman matches. She made six and took 1/8 in the first match, and was then run out for 27 in the next game.