android -java.io.IOException: Canceled when disposed

I'm using android architecture component ,rxjava and retrofit with mvvm structure , i'm new in these fields by the way

the problem I've is this , I'm disposed my disposables in viewmodel ,the problem is this , it'll triggered when I go from activity to activity or close the application and it'll not restart again when it reopens the activity, so I lost the connection and I get FAILED: java.io.IOException: Canceled error when I want to use the api connection again .

this is my code:

class CategoryViewModel(private val model:CategoryModel): ViewModel() {
private lateinit var catsLiveData:MutableLiveData<MutableList<Cat>>

fun getCats():MutableLiveData<MutableList<Cat>>{
    if(!::catsLiveData.isInitialized){
        catsLiveData=model.getCats()
    }
    return catsLiveData;
}

override fun onCleared() {
    super.onCleared()
    model.clearDisposable()
}

this is my model class where I get the data from internet :

class CategoryModel(
    private val netManager: NetManager,
    private val sharedPrefManager: SharedPrefManager) {

private lateinit var categoryDao: CategoryDao
private lateinit var dbConnection: DbConnection
private lateinit var lastUpdate: LastUpdate
private var list: MutableLiveData<MutableList<Cat>> = MutableLiveData()
public val compositeDisposable= CompositeDisposable()

fun getCats(): MutableLiveData<MutableList<Cat>> {

        return getCatsOnline();


}

private fun getCatsOnline(): MutableLiveData<MutableList<Cat>> {
    Log.v("this", "online ");
    val getCats = ApiConnection.client.create(Category::class.java)
    compositeDisposable+=getCats.getCats(sharedPrefManager.getUid(), lastUpdate.getLastCatDate())
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(
                    { success ->
                        list += success.cats

                    }, { error ->
                Log.v("this", "ErrorGetCats " + error.localizedMessage);
            }
            )

    return list;
}


fun clearDisposable(){
    if(!compositeDisposable.isDisposed){
        compositeDisposable.dispose()
        Log.v("this","disposable called");
    }
}
}

what is wrong with this ?

from android -java.io.IOException: Canceled when disposed