Electrum shouldn't be rebroadcasting your transaction but the nodes may be rebroadcasting it for some time I think.
Yes, you should be able to double spend with a higher fee. It the transaction isn't showing in Electrum, this is an easy enough process. It could also be done if you enabled replace by fee. Otherwise, it can be more difficult. Sometimes restoring the wallet from the seed will allow you to respend the inputs. Eventually the transaction should drop out of the mempool and I would think that it should be pretty soon if its already been 2 weeks.
Unless majority of the nodes has dropped your transaction, you cannot spend it since it basically cannot be propagated throughout the network. You have to get some of the nodes to drop your transaction or a miner to accept your transaction for it to work. Restoring the seed from wallet will just load the transaction back in again so it wouldn't work either.
If anyone rebroadcasts the transaction periodically, it will not be dropped until it stops.