Adding new key

I am trying to add some new keys and find words similar to these keys. I was hoping do something on the following lines, for example:
```
vec=s2v['women|NOUN'] + s2v['king|NOUN'] - s2v['men|NOUN']
s2v.add("my_own_key|NOUN", vec)
s2v.most_similar("my_own_key|NOUN", n=10)
```
The second line throws an error though:
```
File "vectors.pyx", line 295, in spacy.vectors.Vectors.add
ValueError: [E060] Cannot add new key to vectors: the table is full. Current shape: (3387194, 300).
```
Not sure how to do such simple vector operations as above in sense2vec.