Both Uses of

mischievous
in
Great Expectations

I am afraid I was ashamed of the dear good fellow,—I know I was ashamed of him,—when I saw that Estella stood at the back of Miss Havisham's chair, and that her eyes laughed mischievously.†
p. 106.6 *

mischievously = in a manner that playfully causes minor trouble

Now, as they went along, Herbert reflected, that I might, after all, have been brought there on some genuine and serviceable errand tending to Provis's safety, and, bethinking himself that in that case interruption must be mischievous, left his guide and Startop on the edge of the quarry, and went on by himself, and stole round the house two or three times, endeavouring to ascertain whether all was right within.†
p. 459.7

Definitions:

(1) (mischievous)
playfully causing minor trouble; or describing the smile of someone doing so

Much less commonly, mischievous can reference real harm without any sense of fun. But in modern writing, that usage has largely shifted to other words like malicious, destructive, or damaging.
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

In law, mischievous references a property crime such as vandalism or graffiti. Very rarely, the word can reference someone or something causing serious damage.

In archaic literature mischievous often refers to bad behavior without any connotation of playfulness or of the harm being minor.