The Reds endured an up-and-down first season under new boss Louis van Gaal, with an indifferent start culminating in a strong second half of the campaign which has saw them return to the Champions League at the first time of asking.
That was arguably the remit for the Dutchman, who replaced David Moyes after his sole year in charge at Old Trafford saw them finish seventh. Van Gaal went on to spend £150m in the summer to bring in the likes of Angel Di Maria, Falcao and Ander Herrera, but Neville believes further spending will be needed for a title push next year.
“People say he’s spent £150m, but I think it needs another £100m this year,” he said.
“I think the job was that big, the rebuilding job was that big because of all those old players leaving and retiring, Sir Alex leaving and the transitional year under David Moyes. It was the biggest rebuilding job for a long time.”
The former defender also says that the Dutchman will not be judged until next year, such was the task facing him this season.
Having succeeded in returning to the Champions League, van Gaal has so far impressed, but next season will be an altogether different story, with many expecting a title challenge from his side.
And Neville says the fans in particular will be expecting more after an overall average season this time around.
“The supporters will want more next year,” he added.
“This year I think is when van Gaal will be judged, last season he’s succeeded in terms of those four games, Tottenham, Liverpool, Manchester City and Aston Villa. That’s when he really produced, but apart from that they’ve actually been pretty average.”