This sentence is confusing me a bit. Let me try to take it apart.
代用 -> Substitution
できる -> to be able to do
って -> somebody said / if … then / as for (or maybe と -> if; when / and / with
聞いた -> to hear
こと -> particle indicating a command
ことあったっけ might be actually ことがある -> indicates an had before experience
け -> particle indicating that the speaker is trying to recall some information
I’m at a loss here and can’t figure out a useful sentence.
I get, that she’s using the newspaper as a substitute for a litterbox. But I simply can’t figure out how the ことあったっけ and 聞いた fit’s in there.
Maybe something like: You can use this newspaper as a substitution to deal with your business instead of the last time. Something along those lines. And excause my lack of nice english sentence building ^^’