random change of PRNG seed during cyphering process

I use a home made python script for private local storage using XOR one-time-pad. The key file is generated by using the PRNG provided by the "random" built-in module of python. As the size of the seed is limited in the PRNG, the number of possible seeds is also limited and then introduces a weakness against brute force attack regarding the increasing power of calculation tools. Do I increase the strength of the script if I change randomnly the seed every two bytes (as an example) ? The script become slower but it is not a problem in my situation.

fct used : SystemRandom().randint(0,255)