You should not ever expect an LLM to actually do what you want without handholding, and randomness in particular is one of the places it fails badly. This is probably fundamental.

That said, this is also not helped by the fact that all of the default interfaces lack many essential features, so you have to build the interface yourself. Neither "clear the context on every attempt" nor "reuse the context repeatedly" will give good results, but having one context producing just one-line summaries, then fresh contexts expanding each one will do slightly less badly.

(If you actually want the LLM to do something useful, there are many more things that need to be added beyond this)