如何在不重启jupyter笔记本的情况下在Keras中重新训练神经网络？

import keras
from keras.models import Sequential
from keras.layers import Dense
from keras.callbacks import ModelCheckpoint

model = Sequential()
model.add(Dense(64, activation='relu', input_dim=100))
model.add(Dense(64, activation='relu'))
model.add(Dense(10, activation='softmax'))
model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])

checkpoint = ModelCheckpoint('model.h5', monitor='val_loss', save_best_only=True)

model.load_weights('model.h5')

model.fit(x_train, y_train, validation_data=(x_val, y_val), epochs=10, callbacks=[checkpoint])