Either they have a preterist fulfillment or only parts of them are fulfilled, which is it?
By preterist I take it you mean partial preterist, otherwise I have a different answer.
Like dispensationalism or amillennialism or any other –ism, orthodox/partial preterism is not monolithic.
Speaking as a partial preterist, the details as to which parts of (for example) Matthew 24 have or have not been fulfilled in the events of AD70 is a matter of discussion and interpretation. Some take all of Matthew 24 as being fulfilled. Others, like myself, see the AD70 fulfillment only up to v. 34. V. 36 and beyond refers to the second coming.
That's my view, and your mileage may vary.