Manchester United are hoping to raise the price of Marcus Rashford's transfer to Barcelona as doubts are emerging over the initial deal struck with the Red Devils last summer. Rashford made a blistering start to his loan move after making the switch from Manchester to Spain last summer, raising the prospect of clinching a permanent move to Camp Nou for €30m (£26m/$34m).But Rashford has gone off the boil lately, starting just once within the last month and last registering a goal or assist towards the end of January. And according to leading Spanish newspaper Marca, It has led to the prospect of Barca making a U-turn and backing out of the agreement they struck with United last summer to sign the forward for €30m and instead agreeing another loan deal, which would then make his price rocket should they decide to eventually buy him permanently.Barcelona president Joan Laporta cast doubt on signing Rashford permanently in an interview with Youtube channel Jijantes on Friday. Laporta, who is hoping to be reelected on Sunday, floated the idea of Barca arranging another loan for the England international, subject to agreement from sporting director Deco. "We could extend the loan, it depends on what Deco wants to do," he said. "There are ways to do it, such as paying a part of the buy-out clause with United and then seeing about the rest. We are looking into the operation."Barca have already agreed personal terms with Rashford in the event of signing him permanently in the summer, meaning that it would be the simplest of options and would just be a matter of paying the buy-out clause. But all the groundwork laid last year would go out the window if they back out of the deal and look to sign him on loan again. It would mean renegotiating his salary and another loan deal would be subject to Rashford giving it the green light, which would be easier said than done as he has set his sights on making the move permanent. Add GOAL.com as a preferred source on Google to see more of our reportingThey would also have to negotiate with United once more. And that's why United are 'rubbing their hands together' in light of Laporta's latest declarations, according to Marca. If Barca want to modify the agreement they have to bear in mind that Rashford's market value has since risen way higher than the €30m agreed last summer as he has scored 10 times and set up a further 13 goals for the Blaugrana. Therefore, if they want to renegotiate, his price is likely to have risen significantly. However, sources consulted by Marca believe it is unlikely that Barca are going to back out of the agreement, although no decision will be made until the end of the season, when they can make a thorough assessment of whether or not the loan  has been a success or not and whether a permanent deal is a wise move.