If that's true I think the price of a Litecoin is going to rise again

The current price is about $4,34 (according
http://coinmarketcap.com/ ). It looks like it's only increasing as the Bitcoin is rising. So, I would say, let the Bitcoin rise

Completely opposite of the correct analysis you have there, as BitCoin rises LTC and other alt coins always decrease. When BTC decreases, then LTC and other alts increase. I think it's going to change in the future but that's the current trend right now.
In terms of USD, all cryptocurrencies have been rising steadily.
The alts don't always decrease with rising BTC. I disagree partly because in the past (last March and April after BTC broke 31 dollars) there were periods when LTC/BTC ratio increased with stable or increasing BTC/USD.
I posit that this has to do with the psychology of crossing the previous high. Prior to last March when BTC was below 31 (the old high) and still recovering from its last big crash rising BTC/USD resulted in falling LTC/BTC. Everyone was excited to see BTC rise and abandoned LTC, but once BTC broke 31 and pushed higher and higher the price kept getting more expensive and folks started looking to alt currencies (like LTC) to buy in the speculative hope that they could get big BTC returns by speculating in alts. And/or those who had large BTC positions were looking to diversify especially as BTC reached ever higher toward 266 peak. If this is correct our recent cross of 266 puts us in this same environment. Folks who are putting funds in to buy BTC are saying " darn I thought I would buy at 300 or 200 but now its 400 and we may be nearing a top. Or folks who have made alot in BTC and now start to fear a top is near and they diversify a bit. This may not be the case but if it is we should see big rises in LTC/BTC soon.