I think ぺろりん here is just being used for nonsense sfx, which goes with her personality. It's perorin, which is normally the sfx of licking something or eating it up, which obviously doesn't apply here. There's a vocaloid song called Perorincho!, for instance see https://lyricstranslate.com/en/perori-n-cho-love-eater.html But she's not eating or licking anything, so either it's a 'tee hee' about how she's moving like a licking tongue, or it's just treating pe-ro-ri-n! as bw-oi-oi-ng!