在使用AppAuth Kotlin库开发Android应用时，可以通过以下步骤处理过期的访问令牌和刷新令牌：

1. 在AuthorizationServiceConfiguration中配置授权服务器的授权和令牌端点。

val clientId = "your_client_id"
val redirectUri = "your_redirect_uri"
val authorizationEndpoint = "your_authorization_endpoint"
val tokenEndpoint = "your_token_endpoint"

val serviceConfiguration = AuthorizationServiceConfiguration(
    Uri.parse(authorizationEndpoint),
    Uri.parse(tokenEndpoint)
)

2. 使用AuthorizationRequest构建授权请求。

val authorizationRequest = AuthorizationRequest.Builder(
    serviceConfiguration,
    clientId,
    ResponseTypeValues.CODE,
    Uri.parse(redirectUri)
)
    .setScopes("your_scopes")
    .build()

val authorizationService = AuthorizationService(context)
val intent = authorizationService.getAuthorizationRequestIntent(authorizationRequest)
startActivityForResult(intent, AUTH_REQUEST_CODE)

3. 在接收到授权响应后，通过AuthorizationResponse和AuthorizationException创建TokenRequest。

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    if (requestCode == AUTH_REQUEST_CODE) {
        val response = AuthorizationResponse.fromIntent(data)
        val exception = AuthorizationException.fromIntent(data)

        val tokenRequest = response?.createTokenExchangeRequest() ?: throw IllegalStateException("Authorization response is missing")

        val authService = AuthorizationService(context)
        authService.performTokenRequest(tokenRequest) { tokenResponse, exception ->
            if (tokenResponse != null) {
                val accessToken = tokenResponse.accessToken
                val refreshToken = tokenResponse.refreshToken

                // 保存访问令牌和刷新令牌
                saveTokens(accessToken, refreshToken)
            } else {
                // 处理异常
            }
        }
    }
}

4. 当访问令牌过期时，使用刷新令牌请求新的访问令牌。

val refreshToken = getRefreshTokenFromStorage()

val tokenRequest = TokenRequest.Builder(
    serviceConfiguration,
    clientId
)
    .setGrantType(GrantTypeValues.REFRESH_TOKEN)
    .setRefreshToken(refreshToken)
    .build()

val authService = AuthorizationService(context)
authService.performTokenRequest(tokenRequest) { tokenResponse, exception ->
    if (tokenResponse != null) {
        val newAccessToken = tokenResponse.accessToken

        // 更新访问令牌
        updateAccessToken(newAccessToken)
    } else {
        // 处理异常
    }
}

注意：在实际开发中，需要根据服务器的要求和令牌的有效期设置相应的参数和逻辑。