Electrum uses python-ecdsa for signing, and python-ecdsa uses RFC 6979 deterministic k signatures.

This means that for any given message (transaction) and private key, the r value will always be the same. However, inversely, if the message is different, or the private key is different, it is guaranteed (as long as SHA256 is not broken) to be different.

Since the exploit of the r values requires 2 different transactions signed by the same private key with the same r values, it is impossible for 2 different transactions to have the same r value using RFC 6979. (in theory)

However, you should not reuse addresses, as it lowers privacy for yourself AND the privacy of those you send money to. (which is not nice, now is it.)