There's been conflicting reports ever since Resident Evil: Retribution 3D was announced whether Sienna Guillory would be back as Jill Valentine in the sequel (she popped up at the end of the last film, Resident Evil: Afterlife), and now the actress herself has given fans an update on the matter.
Shock Till You Drop points out a tweet that Guillory sent today to her followers saying:
"Big day tomorrow! Meeting Paul Anderson and Jeremy Bolt and Robert Kultzer to see what my future looks like..."

- Screen Gems
Sienna Guillory as Jill Valentine in Resident Evil: Afterlife.
As STYD points out, "Guillory's 'future' in Resident Evil: Retribution, the fifth Evil film, had been called into question when a report broke that she was going to be replaced. This was met with a negative reaction from the fans hoping she would reprise her role. But her recent post can be construed as good news."