Be Here Now follows Whitfield and his family as the actor underwent treatment for his cancer and travelled to India to experiment with Eastern medicine.
An appeal to raise $200,000 to complete the film's shooting, editing and post-production was launched earlier this month.
The current total - as of June 28 - stands at $244,515 (£157,645), donated by 4,182 separate contributors.
With 25 days still remaining on the film's Kickstarter appeal, organisers are encouraging fans to continue donating until the end date of Monday, July 23.
"We set our goal as a conservative amount just to complete filming and edit the film because we wanted to make a humble approach to asking the public, fans and our supporters for help," a statement on the appeal's official site read.
"Anything that we raise over that will go towards helping us fulfil our goal of distributing and marketing the documentary as widely as possible."
Whitfield played the title role in the first season of Starz drama Spartacus, but was later diagnosed with non-Hodgkin lymphoma and passed away in September 2011.
> Spartacus to end after upcoming third season
Watch a trailer for Be Here Now below: