she said this in a recent interview:

am currently working on ..
I am currently shooting a comedy called Fired Up. Its a cheerleading movie,with lots of laughs. Also I will be shooting a movie in New Orleans in June that centers around the celebration of Mardi Gras, appropriately titled Mardi Gras. On April 25th, Harold and Kumar Escape from Guantanamo Bay will be released, it's a real hoot! I will also be returning to One Tree Hill next month.

for the complete interview:

Source: http://beautyinterviews.com/my-beauty-secrets/danneel-harris

Ok I'm trying not to read spoilers but when I saw this I had to.

That's awesome news! I can't wait.

Does this mean she's going to be in the end of season 5 or is this season 6? I know she is going to be in season 6.

we don't know if she's gonna be in Season 5...or if she's gonna play a big part of season 6 (we've read she'll be credited as a main cast member again but not sure at all) ..

whether or not this is for S5, depends on the scedule they work with ... if she says she'll be back next month..;than that means that she'll be onset in may (and isn't the filming of S5 sceduled for the ending of May?) ...